Final Cut Pro libraries

Hi,

I'm doing a 40 minute video and the library has reached 700GB! As my entire clip folder (left in place in the settings) is about 120GB, it's not because I'm making an 8K epic.

I'm saving everything to an external drive. The latest created library folder is 700 GB and there are several other, older ones with anything up to 60GB, clogging up the drive. These all refer to the same library. Can I safely delete those older folders without destroying the project?

I've also looked at the library management pane (see pic attached). It's showing where the huge amount of data's coming from. Someone on a forum suggested going File > Delete Generated Clip files to get rid of old stuff I don't need, such as backups and render files. Is this good advice?

Thanks in advance for any help. There seems to be little info on the web about this storing, managing and backing up libraries. The manual's great if you already know what you're doing!

PETE