@sumana Cured resin will typically pop cleanly off of the bottom polycarbonate surface. Use a rigid plastic "tool" such as a plastic putty knife or a credit card edge. Afterwards you can clean the surface with isopropyl alcohol. If excess amounts of alcohol are used, be sure to let the unit sit open for a while before using it.
It is best to avoid putting uncured resin in the chamber. A thorough rinse in isopropyl alcohol should avoid this from happening.