The VG taste itself will leave on its own very fast, i just switched from VG to PG, all i did was blow it out then simply held the atty under hot tap water for 30 seconds (With tweezers of course not my fingers cuz it kinda burns) and then reblow it out and stuff the tip of a tissue in the open part of the atty with that openening facing down for a couple hours.
When its dry, simply drop a couple flavored PG drops (3-5) in the opening part and take a couple drags. I'd be EXTREMELY surprised if any VG taste is left after that and if there is, it will leave in the following 5-10 drags.
Lingering FLAVORING of the VG liquid though thats another story, if the taste is smooth, this method will work. If it's something strong like mint or cinnamon, it might take a couple more drags and re-drips but it works for me.