Extra themes – ok or bad?

I know I am a newbie here, but I’m just wondering, if you keep extra themes in your WordPress setup, will it add bloat to your site? Can these other themes provide a security risk even if they aren’t activated?

I imagine it’s best to delete any theme that aren’t in use, but I’m noticing a lot of unused themes in other setups, so perhaps it doesn’t really matter?

Thankyou!

Any extra code on your server is a theoretical security risk. Instead of checking each plugin and theme if they are security risk even if they are not active, it is much easier to just delete them.

This of course should not prevent you from backuping them first in case you will decide that you need them in the future 😉