Could not initialize Photoshop because the scratch disk are full

From the Adobe forum

Since you cannot start Photoshop, you cannot change the scratch disk allocation in its preferences. Luckily for you, the engineers have devised a shortcut to fix that: Hold down CTRL+ALT(PC) / CMD+OPTION(Mac) as soon as Photoshop starts to get this menu:

Select another disk with more room but do not forget the clean the files clogging up your hard drive, as described in the other messages.