Answer is NO. It won't affect the original/main repository where you forked from. (Functionally, it will be incorrect if such an access is provided to a non-owner).
Just wanted to add this though.
Warning: It will delete the local commits and branches you created on your forked repo. So, before deleting make sure there is a backup of that code with you if it is important.
Best way would be getting a git backup of forked repo using:
git bundle
or other methods that are familiar.