Working in aviation for 20+ years I have learned no 2 sealants are the same. What removes one "silicone" caulk mat not remove another brand since their formulas may be very different.
Lexel is a "rubber" sealant but is not silicone! The following link (http://www.sashcosealants.com/consumers/questions.shtml) is an FAQ page on a few sealants, Lexel among them. One states: "19. How can I remove Lexel?
Answer: Not easy! Cut bead out with razor blade or sharp knife. Clean residue with paint stripper (apply and let it work for a few minutes, then scrub out any residue left on surface.)"
How the stripper would affect the plastic laminant countertop would depend on the stripper. Check the label!! Instead of an abrasive I would try a sturdy cloth to scrub with, like canvas, in the hope to not mar the laminant countertop.
This link has a good description of Lexel: