Clean Up My WordPress Website

I run a busy WordPress website with a lot of user activity. The website has operated continuously for 8 years, and has consequently gone through many WP updates. Recently I tried to install and activate BuddyPress plugin on the site, but upon activation, the entire admin area went blank. The only solution to that was to delete BuddyPress using FTP. Subsequent tries to activate the plugin resulted in the same blank screen for the admin area. It would appear that over time, as plugins were being used, then deactivated due to discontinued support, various uncanny residue was left in the database and/or elsewhere. That apears to cause the issue with my not being able to activate BuddyPress. I'm looking for a well rounded problem solver, with thorough knowledge of WordPress to clean up my site off obsolete crap, while not breaking its otherwise unshakable stability and usability, so I can activate and set up BuddyPress on it. Please note - this is an 18+ website with content intended for mature audiences, although it is not pornographic. Make sure you are over the age of 18 and fine working on a website with adult only content. I prefer dealing with providers who don't bid with a cut and paste letter.