Why resign when you already have plans to re-apply in a few weeks? Being a good staff member requires a lot of hard work and dedication to the server you're staff on and definitely isn't for everybody, and if you were actually on track for a demotion it sounds like you already have some things to work on.
Instead of focusing all your energy on getting staff again in these next few weeks I would take the time to show people you're really making improvements and changing in a good direction. Don't apply for anything, just play on the servers you enjoy, be friendly, respect the rules, and when you feel you're prepared and ready to try to be a staff member again then apply. There's also many members of this community with years of staff experience, don't be afraid to reach out and ask for some tips and advice.
Good luck.