Plunger
The easiest way to unclog a drain is to use a plunger. Fill the tup with about an 4 inch of water. Rapidly plunge the drain about a dozen times. If the water doesn't drain, repeat the process.
Auger
On floor drains, unscrew the drain and feed the auger down the drain until it reaches the blockage. Turn the auger clockwise and remove the auger slowly. Continue this process until water drains properly.
If your tub has a pop-up drain lever, remove the overflow cover but taking out the screws with a screwdriver. Feed the auger down the drain until it reaches the blockage. Turn the auger clockwise and remove the auger slowly. Continue this process until water drains properly.