As for the termination part, call the WS and ask them when the deadline is to terminate your contract, where to send the letter and to whom. If you still get a paper WS book, you may find this information on an obscure page.
At least thirty to 45 days, send a CERTIFIED letter with your name, company name, address, phone, fax, and WS ID number and tell them you are terminating your contract effective ______________. Send a copy to your WS rep, his/her boss, customer service and anyone else you can think of. You can also send an e-mail and a message through the general messages. The certified letter is the most important but I prefer overkill when it comes to documentation.
DO NOT FILL ANY ORDERS on or after the deadline date no matter what. The day after the deadline, remove their software from your computer.