mishandle

(verb) make a mess of, destroy or ruin. Synonyms: botch, bodge, bumble, fumble, botch up, muff, blow, flub, screw up, ball up, spoil, muck up, bungle, fluff, bollix, bollix up, bollocks, bollocks up, bobble, louse up, foul up, mess up, fuck up. Examples: "I botched the dinner and we had to eat out." "The pianist screwed up the difficult passage in the second movement."

(verb) manage badly or incompetently. Synonyms: mismanage, misconduct. Examples: "The funds were mismanaged."