UPDATE!!! this code has been updated >> see the new code && video in the unfriending tutorial
below r steps && code for quickly ( relatively ) deleting ur activity log
go to ur activity log && pic a sub-section ( Photos, Likes, Comments, Search, etc. ) rather than filtering by "All" or "Your Posts", these sections r too big && when i tried it generally crashed my browser. When ur in one of the sub-sections scroll down till u load up about a month or two of content ( if u load 2much content && try to run the scripts below it can crash ur browser ...feel it out, find a sweet spot )
next copy+paste the code below into ur console && press enter
this will automatically click the "edit" buttons on each entry for u which opens up the submenu. u might not see the submenus ( cause they're hidden ) or u might notice them popup on the top-left corner of ur window ( #glitch ), but when the console says "undefined" then u'll know they're there.
after that, copy+paste the code below ( then click enter ), this will open up all the coresponding dialogue boxes ( they'll be stacked ontop of the other, so it may look like only one is open )
NOTE: if ur in the "Likes" sub-section u might not have dialogue boxes, u'll notice a bunch of ur likes getting 'un-liked', && at this point u could refresh ur page && do another batch. if ur in any other section continue to the next steps...
if/when the dialogue boxes have finished loading ( && this may take a minute ) some of the dialogue boxes might have "untag" checkboxes ( similar to the tutorial for untagging urself from photos ), in case u do have those, copy+paste the code below ( && hit enter )
u may also notice that the dialogue boxes ( && the background ) become hard to see b/c of the layers of semi-transparent black stacking on each other, to remove these ( which helps to be able to tell when the dialoge boxes have finished loading ) use the code below
then copy+paste the code below ( && hit enter ) to automatically delete/unlike/untag the posts ( 'likes' won't open dialogue boxes, but posts which requre 'delete'ing or 'untag'ing will )
sometimes ( say with "Notes" for example ) there may be a second set of dialogue boxes so u may have to do this last step twice. then refresh ur page && repeat with the next batch of posts