How do the words 我主張制止不了就放任 piece together?
我 = I
主張 = propose; suggest; say
(如果;既然) 制止不了 = (if; since) it can't be stopped
就放任. = then/just let it be

我主張制止不了就放任 - I say if/ since it can't be stopped, just let it be