Update RELEASE.adoc with instructions to delete unused branches and t…

…ags (IntersectMBO#6230)

RELEASE.adoc

@@ -103,6 +103,10 @@ Another example is if a security audit is done on `rc1`, and the changes in `rc2
 - Click the `Run workflow` button on the right, enter the new release version and confirm
 - Ensure that the action completes successfully
 
+11. Delete unused brances and tags 
+- If it was created, delete the `release/*` branch locally and on GitHub
+- If they were created, delete any release candidate `-rc*` tags locally and on GitHub
+
 === Patch Releases
 
 Suppose we are releasing version `x.y.z.w`.
@@ -118,6 +122,7 @@ If so, create branch `release/x.y.z` from the `x.y.z.0` tag.
 6. Open a PR for updating the cabal files and the changelog files.
 7. Once the PR is merged, tag the commit `x.y.z.w`, and open a PR in the CHaP repository for publishing the new version.
 - If issues are found, fix them on master, backport the fixes to `release/x.y.z`, and go to step 5.
+8. If it was created, delete the `release/*` branch locally and on GitHub
 
 === Release QA Process