Allow to clear all notification filters with one button

This issue is about the list of notification filters displayed for a user in the user profile.
Currently, there are individual delete buttons allowing to delete one such filter but there is no way to clear all the filters. When there are hundreds of such filters, one may want to remove them all and this is not possible.

One of the easy ways in which a user can find themselves with a bunch of filters is the Autowatch, which is enabled by default.
So it's enough to start a wiki and start working a little on it for an administrator to find themselves with a loooooong list of filters (because of autowatch) and no easy way to clean it up when they realise the situation.