I wanted to remove the brake fluid from the master cylinder but I don't know how to remove the strainer. Does anyone know what to do?

 

Open the brake fluid resevior. You can use a turkey baster if you just want to remove a little.

Otherwise attatch a 1/4" tube to your bleeder barb and turn it 1/4 turn or so untill the fluid flows. Have someone pump the brakes, but don't let the pedal touch the floor.

 

Nice photo!
There is a cover (strainer) in the reservoir that I want to know how to remove.

 

the strainer does come out, you just have to maybe pry it out a little.