All you have demonstrated is that you have not kept sufficiently in practice on multi engine flying. Hire a twin with an instructor for an hour or two, go away and do a few engine failures straight and level, practice some SE flying, including turns, climbs, descents, get used to only having a single engine, then come back to the circuit and start with an engine failure on climb out with climb power, when you both think you are up to speed take the engine failure shortly after rotate.
Flying is not a natural environment for man, you have to keep current or you lose the skill.
No need to cancel your licence, just go practice and regain your self confidence, you have done it before, remember?