I have a used set of weights at home and they are in good condition, but some of the plates have a bit of rust on them. I was wondering if there is a safe way to remove it or should I just leave it alone.

Here's some ideas,

https://www.youtube.com/watch?v=xYBZ9a6eOHQ

https://www.youtube.com/watch?v=F07HTPMm2QI

AND

https://www.youtube.com/watch?v=fUYr_7SwGms&list=PL-YYS93SB7-SQlIsFMTyIvUyDGCQa4abM