firstly check that you have solid lifters on your engine, if you dont see a shim then you most probably have 2C turbo engine type hydraulic lifters which do not require adjustment.
The lifters in the above pic show a slit for picking the shim up with a tiny set of pliers, I personally never wrestled the shim out - the valve spring force is too high and if your screwdriver or whatever you are using as a tool breaks off or slips you can fracture the camshaft. Best way to do it if you lack the screw type press tool is to remove the camshaft - you can do this very easily too, use some cable ties to tie the belt on the pulley and undo the pulley - also make sure the pump pulley doesnt let go of the belt.
The way I did it was very simple, first check all clearances and write them down, then remove shaft and inspect shims - replace or swap around as necessary.
For you - make sure you have solid lifters.