Hi there,
the best is a bracelet removal tool but if u dont have that handy u can manage it also with a small screwdriver ...
turn the watch upside down on some soft place not to damage it and locate the opening of the end links on that back that will expose the pins ... i presume we are talking 16610 modern sub !
When u will see the pinn slip in the screwdriver and try to push it away from the case this shoud loosen it up and out of the hole , do the same on the other side and pull out the bracelet ... its easy !
Be pacient and carefull afcourse to avoid damaging the case ...
NOw that said if u have a vintage sub theneven easyer ... vintages have drilled lug holes through the case ... use an office paper clip to push the pin out of the case from both sides and remove bracelet .
Hope this helps , kind regards laz