I am not sure what the laws are for Wisconsin (I'm in Texas) or the details of the contract you signed with the seller, but I would think the general process is the same. If you signed a contract with the seller and cancelled your earnest money check so that it could not be deposited you are most likely in breach of your contract. (Consult an attorney, YOUR attorney, for review of the contract before paying money to anyone.) If the earnest money check had been deposited and you also PAID (additional check made payable to owners) for an option (time in which to do inspections) in the contract, you likely have the unrestricted right to cancel the contract FOR ANY REASON, but you have to do it through the correct process. A real estate agent is required to deposit an earnest money check and have the contract receipted within a certain time frame after a contract is signed.
If you would have "opted out" during the option period stated in the contract (Again, that is how the process works in Texas), you would have received your earnest money deposit back, but would have taken about 30 days (a release is usually signed by both parties for it to be released). Not sure if your state closes at title companies or attorney offices... so that may change the process some.
YOUR attorney should be able to advise you on the best way to proceed.