I'm assuming that 止めりゃしない was misheard as 止めらしない, where that りゃ is a contraction of りや to りゃ.
Instead of 止めらしない it should be 止めやしない. I've seen it written and heard it said as 止めりゃしない but I suppose you can consider that a "slang mistake" treating 止める as a go-dan instead of ichi-dan. (止めやしない is more common).
止めやしない is [RYK(masu form)+や+しない], which has the same meaning as 止める(など)はしない [RTK(plain form)+(など)+は+しない] "I won't do anything like try to stop you," so you will hear both forms from time to time.
The りゃ comes in if it's a ラ行 godan verb because りや will contract to りゃ:
蹴りゃしない, which again is the same meaning as 蹴るなどはしない
Other examples with varying degrees of contraction:
逃げやしない (does not contract) == 逃げるなどはしない
行きゃしない==行きやしない (sometimes contracts) == 行くなどはしない
蹴りゃしない (always contracts) == 蹴るなどはしない
However, the entire construction is fairly rare when it's not 止めやしない, the sheer frequency of that words use probably contributes to the "incorrect slang" version of 止めりゃしない