Heeeey,
I like those little cacti. They're cute but those flowers are awful.
I've gotten them off by 'wiggling' them a little with eyebrow tweezers every day or so. Loosens the flower and the glue over a few days so you can just pluck it off.
Another tick I found is take them into the bathroom with you when you take a shower or bath. Cacti love humidity not necessarily water and the steam and humidity from your shower does a good job on the loosening up of that nasty sticky and hard glue. Don't recommend the steam bath every day but once or twice won't do any harm.
And see......for all those who aren't fans of Ferocacti look how cute they can be.
repurposed old pots, a few rocks laying around and some aquarium pebble. Everyone of these either a bin, rescue or just a cheap plant. They're doing better then my more expensive ones.
