I have to remove an existing right angle waste fitting which is fixed vertically to the below floor drainage system. This only has to be removed to allow the toilet to be put in place to allow it to be connected with a same size right angle fitting. Problem is that I can not physically remove the existing fitting. Is it normal to be fixed with adhesive and is it done with a short length of pipe set inside both fittings. If so could I cut through at this point and use a push fit right angle fitting. 
