When a drain is clogged, it may be necessary to remove the bathtub plug to unclog it. Though the process may not be obvious on first glance, removing a modern bathtub plug is easy and requires few tools. Unlike older models, the majority of bathtub plugs today simply twist out of their bases.
Step One
Run water over the drain plug while it's in the upright position, removing any soap scum or other slippery substances that would make it hard to grip. Dry underneath the drain plug with a clean, dry towel.
https://letsfixit.co.uk/14929/how-to-remove-a-bathtub-plug/?utm_campaign=twitter&utm_medium=twitter&utm_source=twitter