Trial won't open and neither will my account

I recently downloaded the trial for photoshop but it refuses to open. I had no probelms with the download but every time I try opening the program its tells me that I need to renew my subscription, and this is based on the adobe account of the previous laptop owner. It does give me the option to sign in to my account, but everytime I sign in it redirects me to a serial number screen. I've deleted all the previous adobe programs under the previous owner's account but that did not help at all, it still tells me the same thing. I am obviously missing something here. Any help would be much appreciated.