First, the police in Ottawa chose not to enforce even basic laws in the area of the protest for several weeks. The result was lawlessness and a total lack of respect for the police. They were being jeered at for putting threatening flyers under windshield wipers one day, and the next they brought in armoured vehicles and riot squads. If the police had consistently written tickets and made arrests from the start of the protest it likely would not have grown as large as it did.
Presently, Trudeau is keeping the Emergencies Act in effect, not because there is an ongoing emergency, but because there might be. He's argued that some of the protesters have not left Ottawa and might return to the protest site if given the chance to do so, but there is nothing in the Emergency act that is required for the police to maintain peace and order. Trudeau wants the act to remain in effect for other reasons apparently.
The opposition is introducing a motion in parliament to end the Act, but that will likely fail unless Trudeau loses the NDP's support. However, the senate could also end the Act at any time. Given that the emergency is over they should do just that. It is entirely unclear what Trudeau hopes to accomplish by holding onto these powers.