i would agree that is can not be readily done without severely damaging the underlying concrete. if properly applies as a liquid, it should have molded itself into all the pores of the concrete and be extremely well bonded. cured epdm is almost completely inert -- no solvent it going to do more than swell it a little.
again, why do you want to remove it? if it is a color / aesthetic issue, you might be able to find a colored coating that will bond to the epdm, although tht will be a challenge
Why would you want to remove the liquid rubber? i'd say even if it is in bad shape and leaking use a belt sander or a grinder smooth out the rough edges and then apply some fabric / pond liner fabric and install a new 45 mil epdm