The spur can be disconnected from where it is supplied from, ie: if from junction box under floor disconnect the live, neutral and earth. If this socket is never ever to be used again you can either remove cable from wall of cut back, then repair any plaster damage to wall and fill in where socket sunk. Or if another socket again disconnect the spur to the socket, the terminal ends can be put in to connection block or cut or removed completely.
If it may be used again in the future, then terminate all the conductor ends using a connection block, 20A or 30A will give you enough room for cable cores and blank socket off.
If you are disconnecting a socket from the ring final circuit, you can connect the ring up within the it's existing box, using 30A connection block live to live, neutral to neutral and earth to earth, then fit a blanking plate (you cannot plaster over this connection!)
If you wanted to remove completely, it would be easiest to remove cable from wall then join them underfloor by use of an MF junction box rated at 32A
http://www.tlc-direct.co.uk/Products/ASJ803.html
(not a standard junction box) As the regulation will not allow standard junction boxes to be used in area that are not easily accessible, for maintenance and inspection and testing.
The other alternative and best way to keep you ring final complete, would be to remove cable from socket, identify where both legs are coming from and install a new cable across those accessories.