stop APE from opening all pdf files

[#1]

I put an old Adobe Photoshop Elements (4) on an old Acer/Vista computer to work on photos.  Massive mistake--every pdf file I click on to open, opens in thumbnail Photoshop panel.  How can I tell Photoshop not to open anything until I drag a file to the app? Or just delete Photoshop from the computer and enjoy access to pdf forms and files.  To open a pdf,  I have to open Adobe Reader, the select the pdf to open.  I cannot just click on a pdf file and have it open.  Photoshop Elements dominates.

[#2]

I put an old Adobe Photoshop Elements (4) on an old Acer/Vista computer to work on photos.  Massive mistake--every pdf file I click on to open, opens in thumbnail Photoshop panel.  How can I tell Photoshop not to open anything until I drag a file to the app? Or just delete Photoshop from the computer and enjoy access to pdf forms and files.  To open a pdf,  I have to open Adobe Reader, the select the pdf to open.  I cannot just click on a pdf file and have it open.  Photoshop Elements dominates.