Open all PDF using Preview instead of Adobe Reader

I recently install Adobe Reader and now all files are opening with Adobe Reader instead of Preview. I want to change the default to Preview for all PDF files. I did choose open with option key down... so that I can select open with... and then chose the option "always open with...". However this only changes the default application for the single file I chose and not to ALL PDF files. When I try to open any random PDF file, it defaults to Adobe Reader, even AFTER I selected "always open with... Preview" on a difference file. Any ideas on how I can make sure the Preview opens for ALL PDF files as default?

Thanks,

Orlando - Chicago, IL