Locked out of my site

Hi. I’m building a site in wordpress, and i installed a plug-in called WP-Client (the free version) but then i upgraded to a pro version and was following the step by step instructions from their site of how to activate the paid version. So i got it installed and activated, but I didn’t realize that i needed to deactivate the free version first. Now all i can see is a message that says “you can’t use the lite version and the pro version together” but i can not get back in to my site to even deactivate the free plug-in. Please help me know what to do now. thank you!