diff --git a/go.mod b/go.mod
index 7e920ac03208e..02f0c46f22e1c 100644
--- a/go.mod
+++ b/go.mod
@@ -69,8 +69,6 @@ require (
 	github.com/mattn/go-sqlite3 v1.11.0
 	github.com/mcuadros/go-version v0.0.0-20190308113854-92cdf37c5b75
 	github.com/microcosm-cc/bluemonday v0.0.0-20161012083705-f77f16ffc87a
-	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
-	github.com/modern-go/reflect2 v1.0.1 // indirect
 	github.com/mschoch/smat v0.0.0-20160514031455-90eadee771ae // indirect
 	github.com/msteinert/pam v0.0.0-20151204160544-02ccfbfaf0cc
 	github.com/nfnt/resize v0.0.0-20160724205520-891127d8d1b5
diff --git a/modules/structs/issue.go b/modules/structs/issue.go
index bd39f9ea444b0..b27c757faa52d 100644
--- a/modules/structs/issue.go
+++ b/modules/structs/issue.go
@@ -99,7 +99,8 @@ type EditIssueOption struct {
 	Milestone *int64   `json:"milestone"`
 	State     *string  `json:"state"`
 	// swagger:strfmt date-time
-	Deadline *time.Time `json:"due_date"`
+	Deadline       *time.Time `json:"due_date"`
+	RemoveDeadline *bool      `json:"unset_due_date"`
 }
 
 // EditDeadlineOption options for creating a deadline
diff --git a/modules/structs/pull.go b/modules/structs/pull.go
index 722d245afc49e..c4ec7d416a9b1 100644
--- a/modules/structs/pull.go
+++ b/modules/structs/pull.go
@@ -88,5 +88,6 @@ type EditPullRequestOption struct {
 	Labels    []int64  `json:"labels"`
 	State     *string  `json:"state"`
 	// swagger:strfmt date-time
-	Deadline *time.Time `json:"due_date"`
+	Deadline       *time.Time `json:"due_date"`
+	RemoveDeadline *bool      `json:"unset_due_date"`
 }
diff --git a/routers/api/v1/repo/issue.go b/routers/api/v1/repo/issue.go
index 1534c45df0a0f..186e66cb8f8c6 100644
--- a/routers/api/v1/repo/issue.go
+++ b/routers/api/v1/repo/issue.go
@@ -458,9 +458,16 @@ func EditIssue(ctx *context.APIContext, form api.EditIssueOption) {
 		issue.Content = *form.Body
 	}
 
-	// Update the deadline
-	if form.Deadline != nil && ctx.Repo.CanWrite(models.UnitTypeIssues) {
-		deadlineUnix := timeutil.TimeStamp(form.Deadline.Unix())
+	// Update or remove the deadline, only if set and allowed
+	if (form.Deadline != nil || form.RemoveDeadline != nil) && ctx.Repo.CanWrite(models.UnitTypeIssues) {
+		var deadlineUnix timeutil.TimeStamp
+
+		if (form.RemoveDeadline == nil || !*form.RemoveDeadline) && !form.Deadline.IsZero() {
+			deadline := time.Date(form.Deadline.Year(), form.Deadline.Month(), form.Deadline.Day(),
+				23, 59, 59, 0, form.Deadline.Location())
+			deadlineUnix = timeutil.TimeStamp(deadline.Unix())
+		}
+
 		if err := models.UpdateIssueDeadline(issue, deadlineUnix, ctx.User); err != nil {
 			ctx.Error(500, "UpdateIssueDeadline", err)
 			return
diff --git a/routers/api/v1/repo/pull.go b/routers/api/v1/repo/pull.go
index 9264c00cec614..6d86105a15d13 100644
--- a/routers/api/v1/repo/pull.go
+++ b/routers/api/v1/repo/pull.go
@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"net/http"
 	"strings"
+	"time"
 
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/modules/auth"
@@ -326,7 +327,7 @@ func CreatePullRequest(ctx *context.APIContext, form api.CreatePullRequestOption
 func EditPullRequest(ctx *context.APIContext, form api.EditPullRequestOption) {
 	// swagger:operation PATCH /repos/{owner}/{repo}/pulls/{index} repository repoEditPullRequest
 	// ---
-	// summary: Update a pull request
+	// summary: Update a pull request. If using deadline only the date will be taken into account, and time of day ignored.
 	// consumes:
 	// - application/json
 	// produces:
@@ -385,9 +386,15 @@ func EditPullRequest(ctx *context.APIContext, form api.EditPullRequestOption) {
 		issue.Content = form.Body
 	}
 
-	// Update Deadline
-	if form.Deadline != nil {
-		deadlineUnix := timeutil.TimeStamp(form.Deadline.Unix())
+	// Update or remove deadline if set
+	if form.Deadline != nil || form.RemoveDeadline != nil {
+		var deadlineUnix timeutil.TimeStamp
+		if (form.RemoveDeadline == nil || !*form.RemoveDeadline) && !form.Deadline.IsZero() {
+			deadline := time.Date(form.Deadline.Year(), form.Deadline.Month(), form.Deadline.Day(),
+				23, 59, 59, 0, form.Deadline.Location())
+			deadlineUnix = timeutil.TimeStamp(deadline.Unix())
+		}
+
 		if err := models.UpdateIssueDeadline(issue, deadlineUnix, ctx.User); err != nil {
 			ctx.Error(500, "UpdateIssueDeadline", err)
 			return
diff --git a/templates/swagger/v1_json.tmpl b/templates/swagger/v1_json.tmpl
index 41e5353ea73b0..17b8eab6c5e28 100644
--- a/templates/swagger/v1_json.tmpl
+++ b/templates/swagger/v1_json.tmpl
@@ -4715,7 +4715,7 @@
         "tags": [
           "repository"
         ],
-        "summary": "Update a pull request",
+        "summary": "Update a pull request. If using deadline only the date will be taken into account, and time of day ignored.",
         "operationId": "repoEditPullRequest",
         "parameters": [
           {
@@ -8532,6 +8532,10 @@
         "title": {
           "type": "string",
           "x-go-name": "Title"
+        },
+        "unset_due_date": {
+          "type": "boolean",
+          "x-go-name": "RemoveDeadline"
         }
       },
       "x-go-package": "code.gitea.io/gitea/modules/structs"
@@ -8660,6 +8664,10 @@
         "title": {
           "type": "string",
           "x-go-name": "Title"
+        },
+        "unset_due_date": {
+          "type": "boolean",
+          "x-go-name": "RemoveDeadline"
         }
       },
       "x-go-package": "code.gitea.io/gitea/modules/structs"