Basin waste removal

[btjtaylor]

Hi all

Does anyone know how I can remove this (photo attached) basin waste?



Unscrewing the top just removes the metal top cover

Sink is draining slowly and my first port of call is to plunge it but when I get the plunger on top it just closes the waste back up!

Hesitant to start pulling and twisting too much before I understand how it works

Thanks in advance

 

[HERTS P&D]

Take off the trap underneath.

Or use a wet vac.

Andy

 

[denso13]

Can't really see clearly, either a long bolt through the grating or a large nut below.

 

[btjtaylor]

Thanks both I tackled the problem from below, it's a wall hung sink so I thought it might be a nightmare to remove the bottom piece that covers the pipes but it wasn't too bad other than some silicone bead around the side of the cover to cut that wasn't achieving much, fortunately it wasnt siliconed to the wall etc!