I have 4 years old Lhasa Apso male dog ,he scared to cut his hair. If you forced to cut his hair he want to bite you. I am already brought the dog to Petco they couldn't handle it.What I should to do ? Thank you

Ask your vet if there is something you can give your dog to calm him down during the process.

What part is he scared of exactly, the process of being held in one place? The sound of the scissors or clippers? etc.

How long have you owned the dog?

There are ways to desensitize them but they can be slow. You need to build up to actually grooming the dog by allowing it to first get used to being on a grooming table, use plenty of treats and make sure the dog associates being on the grooming table with something postitive.

If the dog is afraid of the scissors or clippers you can simply place the grooming gear in the middle of the floor and put some treats next to it. Allow the dog to approach the grooming equipment in its own time and take the treats.
Once the dog is comfortable being near the equipment then you can work up to touching the dog with them, all while giving treats but make sure not to turn the cippers on or use the scissors.
Once the dog is comfortable with that then you can start grooming, again, take your time and use plenty of treats. This needs to be a positive experience.

It can sometimes take weeks or even months to work up to a level where you can properly groom the dog, but once the dog is comfortable with being groomed you should have no more problems.

The same technique can be used for many things from being scared of bicycles, vacuum cleaners, even nail clippers.

If all that fails then unfortunately you would have to resort to the use of muzzles and maybe even sedatives, but desensitising should be your first port of call.