The casino made what I assume is a promise to op that if he could own up and agree on cheating or trying to cheat the casino by operating two accounts, and also writing an apology note on a public forum like this one, that they will allow him withdraw his initial deposit and maybe winnings from slot games.
I guess in that case the casino should at least allow OP to withdraw his/her initial deposit if not the winnings. OP has broken the terms of the casinos and it will be good fate of the casino to allow withdrawal of the initial deposit. I believe most people on this forum who might operate multiple accounts on online casinos should better read the terms and conditions first and avoid creating multiple accounts.