is Malwarebytes free safe to use on my macbook

Yes, absolutely. Malwarebytes is a respected utility for detecting and removing nasties from your Mac. There is a free version available for manual scanning. Automated scanning requires a paid subscription.

It is safe to use PROVIDED you get it direct from the maker, not from any other site (where it could have been modified).

as for what is can remove, try it! it is not complicated to operate.