Safari 8 (Yosemite): If you need to remove a plug-in
If you installed a plug-in and notice that Safari runs more slowly, quits unexpectedly, won’t download files, or has other problems, the plug-in may be the problem.
Stop a plug-in you recently added
You can quickly test whether a recently added plug-in is causing problems by blocking it.
Choose Safari > Preferences, click Security, then click Website Settings next to Allow Plug-ins.
Select the plug-in you want to disable on the far left, then click each pop-up menu on the right and choose Block.
For some plug-ins, you see pop-up menus for different websites, and you can choose to block each one individually. Use the “When visiting other websites” pop-up menu to block all other websites that don’t have individual settings.
Remove a plug-in you recently added
If you determine that a plug-in is causing problems, you can remove it.
Locate the plug-in. Plug-ins are usually installed in one of these folders:
To open this folder in the Finder, choose Go > Computer, open the startup disk (usually named Macintosh HD), open the Library folder, then open the Internet Plug-ins folder.
To open this folder in the Finder, hold down the Option key and choose Go > Library, then open the Internet Plug-ins folder.
Remove the plug-in you recently added.
If the problem is fixed, contact the developer of the plug-in to see if there’s a newer version.