wash one's hands

verb2

1. •
   (figurative) To absolve oneself of responsibility or future blame for; to refuse to have any further involvement with.

   • Sharp[er]. […] Mony is but Dirt, Sir Joseph—Mere Dirt. / Sir Jo[seph Wittoll]. But I profess, it is a Dirt I have vvashed my Hands of at present; I have laid it all out upon my Back. — 1693
2. •
   (euphemistic) To go to the toilet.