In general, wait until they are dried out . nitrogen translocation or retranslocation come into play, and let the plant'recycle'nutrients by moving nitrogen and other useful compounds into storage organs, that can later be used to make new leaves . ( both of those are surprising redlinks, best I can find on WP is a terse statement at the disambig for translocation . . . see e . g . for the idea ).
मोबाइल