If you're working on a protected branch, you won't be able to make irrevocable changes to the branch. You can enable required status checks on the protected branch that will prevent you from merging the pull request until all of the required checks pass.
You can see if your pull request can be merged at the bottom of the pull request's Conversation tab.
- If you're working on a branch with protections enabled by a repository administrator, you won't be able to delete or force push to the branch.
- If the protected branch has required status checks enabled, you won't be able to merge changes into the branch until all of the required CI tests pass.