let him who tied the bell on the tiger take it off—whoever started the trouble should end it
解铃还需系铃人jiě línɡ hái xū jì línɡ rén
比喻谁出了问题，还得由谁自己去解决。Whoever started the trouble should end it. let the mischiefmaker undo the mischief, it is better for the doer to undo what he has done, To untie the bell, the person who tied it is necessary.