Ok...
You are looking in the wrong Library folder. There are two, system and your Home Folder.
Open a Finder window. On the left select your Home Folder (It has a small house icon).
Then on the right open the Library folder then the Preferences folder.
The com.apple.Safari.plist file is there. Just move it to the Trash and relaunch Safari.
~/Library/Preferences
When you see the ~ (Tilde) character, that represents your Home Folder.
🙂