Here's the ladder of solvents that will work - from the most friendly to the strongest and most caustic ( fumes etc.)

Isopropyl Alcohol
Denatured Alcohol
Laquor Thinner
Acitone

The Isopropyl is the most friendly, cheap and non- toxic.
If you have glops of stubborn resadue, Acitone will disolve it ilike it was nothing.

Laquor thinner and acitone will also wipe away your varnish.