Is there a way to quickly delete/disable ALL scheduled Tasks?

Windows 7 (and newer versions) come with a large amount of pre-configured scheduled Tasks. Additionally various software sometimes adds more scheduled Tasks in the system.

Is there a way to disable or delete all scheduled tasks without having to go through them one by one?

Software (Free and Portable):

Autoruns. Not a 1 click solution but certainly a convenient one for navigating and enabling/disabling/deleting what you want.

You can further use it to disable anything you don't want auto-running via other means as well.

I'm not sure if tampering with the schedule service is a complete solution. I think some of the more aggressive bloat-ware turns it on.

Delete the task files manually:

If you really really want to brute force it just delete at will in:

%systemroot%\System32\Tasks
%systemroot%\Tasks

Though some of the Microsoft stuff in there is probably best left intact. I haven't done these wipes personally. But you can back them up and wipe to see if you need any. Some folks disable the service which has almost the same effect as deleting all the tasks.