The only way you can heat and unsolder that connection is if there is absolutely no water and it's open to air.
If you have a torch and a Male Adapter to solder back on, you can disconnect and bend the tubing downward to drain it out. Or just cut the pipe back behind the tubing and solder the MA there.
Some flex connectors with 3/4 ends will work then. NO TEFLON TAPE. The flex connectors with have seals at the ends.