Hello,
Following the documentaion there should be a View menu item called "Show Column Guides" that should allow hiding/showing column guides.
I cannot find it (I'm on Photo persona).
I have enabled 3 by 3 column guides but cannot find a way to switch them on/off other than setting the column/row number back and forth between 1 and the number I need.
Quite unconvenient, I'd say.
Affinity Photo 1.8.3 on Windows 10 x64 (Italian).
Thanks,
Mario