Through some failures trying to remove Bootcamp I've found myself with a 289GB Macintosh HD and a 201GB "Container disk1". I initially tried to erase the extra volume, thinking it would then give me an option to resize the space into MacintoshHD but apparently not, even in recovery mode. When I delete the volume it just leaves behind the container. I guess APFS works differently.
My main Macintosh HD drive is APFS Encrypted if that makes any difference. Id like to reclaim the entire 201.95GB from Container disk1 back into Macintosh HD.