Removing tub drain stopper to unclog drain pipe?

I've done this in the past but forget how. I tried simply pulling up on the stopper, thinking it would release and come out. But, it did not. The drain has been clogged for awhile and draining is extremely slow, which leaves residue on the tub. So, I hope someone can give some advice.

See photo.

 

If im not mistaken, it should be threaded on. Try turning it counter clockwise and is should un-screw.

 

You can also remove the vent plate under the spout. That's an easier route to the clog location.

Clog location circled in red.

 

Yes, stopper will unscrew. May be two parts to unscrew. The cap that you pull up on and then under the cap will be a phillips head screw to get the main body out. So, hold the larger round part and turn the smaller inner part to expose the screw.

Sometimes you can pull all the hair out from the drain opening. Other times, like pete says, remove the overflow cover and fish a snake down the overflow to push or pull the clog out.

 

Thanks for the replies. The knob on top can, as mentioned by one of you, be removed by unscrewing it but this drain stopper has no screw under the knob to remove. So, removing the knob was unnecessary.

So, I took a large plier, large enough to grip the outer edges of the stopper, and proceeded to unscrew it. i found this video helpful since the stopper shown in it is identical to mine.

The hair blocking the drain was all under the stopper. So, once I removed the stopper and removed the hair, the drain was clear. Then, time to do some general tub cleaning.