> Should I set status for this issue for closed with resolution rejected ?

I'll proceed with closing the issue.

> Should I delete branch on my forked git repo ?
> Can I delete my forked git repo ?

Might as well delete the branch, but the forked repo might be useful to keep around should you choose to open a PR to CPython in the future (although you can also just create a new one later). If you are interested in working on something else in the future, I'd recommend looking at the "newcomer friendly"/"easy" issues, or just looking for an existing open issue that you're interested in helping with. In most cases, working with a clearly defined issue is much easier than trying to propose a new one and getting it merged.