No need to do this yet.
Go slow, steady don't be rash everything will be okay!

I have to say it's refreshing to see a teenager into aquariums instead of video games and the like.
Best way to do this is manual removal, scrubbing, water changes.
Hooking up the skimmer is a step in the right direction and we're here if you need help with that.
In no way is a skimmer going to remove nitrate or phosphate but, instead it will help remove things that may cause those issues.
It is still up to you to change water and scrub these rocks, which I KNOW you can do.
Chemicals, rip cleans should always be a last resort and rarely if ever solve anything, especially if you have no experience in either.
We're here for you just take it one step at a time.