A disarmed police force would only be cable to enforcing the law against compliant people. They would just be glorified tax collectors and ticket writers. They could only intimidate people who allowed it. Kind of like the old Death Wish movies where cops were more than happy to seize guns from law abiding citizens but wouldn't touch the gang members threatening them.
On top of that, we would see gangs looking to attack police in groups....intimidate them at the very least. I don't care how well trained a cop is, if 20 gang members attack as a group, the cop is not going to come out well.
That said, even if the street cops were disarmed, the police would keep a core of armed officers and SWAT teams to protect the politicians and take care of anyone they perceived as a vigilante.