How can I remove TickTick's icon from the menu bar?
Run this command in Terminal:

strings -ao /Applications/TickTick.app/Contents/Resources/Assets.car | grep menubar_icon_task@2x.png | awk "{print \$1}" | xargs echo 232+ | bc | \
xargs -I{} echo "printf '\x01' | dd of=/Applications/TickTick.app/Contents/Resources/Assets.car bs=1 conv=notrunc seek={}" | sh


It will narrow the menubar icon down so much that it will become invisible. Ctrl+'mouse drag' the icon to the left most place.

Explanation:
strings finds the position of the icon in the asset container, echo and bc move a few bytes forward to get to the position that is responsible for the width of the icon. printf and dd set that byte to 1 for minimum width.