Put a chunk of flat steel into the refrigerator. When it is very cold take it out and put your assembly on it with the tape casted part facing the steel and press it. PVA will become rigid. Then peel the teflon if it is thin, else peel the tape

Dear Tofiq

If you mean the layer should be deteriorated you can use HF acid. But I guess you need sound detached layer. If so, there is nothing to make you worry.

In my experiment the PVA-injected thick composite layer was detached easily from cast-iron substrate even after pressurizing at 50 bar.

For teflon you may need a tension or compression preloading, Or you can sand-blast the surface prior to deposition.   

Best, 

Hamidreza