Step 1: Go to your Tumblr following page - https://www.tumblr.com/following/
Step 2: Run iMacro Script on loop for as many pages of friends you have [set on loop for around 50 to unfollow 1250 *50x25perpage=1250*
Code:
VERSION BUILD=6011206 RECORDER=CR TAG POS=1 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=2 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=3 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=4 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=5 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=6 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=7 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=8 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=9 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=10 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=11 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=12 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=13 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=14 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=15 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=16 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=17 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=18 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=19 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=20 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=21 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=22 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=23 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=24 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=25 TYPE=BUTTON ATTR=ID:unfollow_button_* WAIT SECONDS=0.5 TAG POS=1 TYPE=A ATTR=TXT:Next WAIT SECONDS=20