Delete stale DB records?

[IngwiePhoenix]

I removed any bridges and bots a long time ago because I switched to just using the messengers directly again after spending more time fighting with the bridges than actually getting stuff done... so now I just realized that half my VPS is just one enormous DB - that being Dendrite's. It's 40GB big. Something tells me that there is a lot of stale data in this...

What approach can I take to slim this down and remove old/unused messages and rooms with their content? For example, I am sure that some old bridged rooms are still there that are joined to by nobody, so it would be great to clear them out to reclaim some space.

Thanks!