If it's pebble dash, a kango spade will take it off - no problems if you damage the background, as you will be giving the whole a scrath coat before the floating. A word of caution, if you have patent reveals go easy in the vicinity lest you break them. But an easier option would be to scud, scratch and float over the existing ....... in which case you'ld break off the patents, scud and scratch, reinstate the reveals and float out as normal. If it is peeble dash ....... then carry on as above!