At least one user of a certain garden site that GardenWeb won't allow me to refer to in a post recommends using a heated Exacto knife to cut through the glue. I think this might be a bit risky.

I think this video uses a much safer technique:

https://www.youtube.com/watch?v=9qKHCg-nYv8

I haven't removed flowers from cacti before, but I've removed plenty of glue from other things. If the technique in the video doesn't work, I'd try my own. I don't think this will damage a cactus, but I'm not 100% certain, so try it at your own risk.

Since the flower is more delicate than the cactus, I'd run the top of the plant under tepid water for a while until the flower is softened, then rub the flower gently until it falls apart and washes away. If you're lucky, the water will also seep between the glue and cactus skin and loosen that bond. If not, a soft paint brush or makeup brush can be used to work a tiny bit of vegetable oil into any spot where there is space between the glue and cactus. Hopefully that'll dislodge it. After removal, I'd wash away the oil with an equally tiny bit of very diluted dish soap. I don't think water, oil, or soap will damage the cactus skin, but likely the glue already did, so you might have s scar.

I Googled "How to remove straw flowers from cactus" for the link above. There were more suggestions, so you might try the same search criteria for more ideas.

Good luck!

The last 2 flowers I removed came off by gently pulling on the straw flower but the plant already had damage from the hot glue that had been used. On some flowers that would not pull off I have cut them off with scissors being careful not to cut into the plant. Then carefully try to remove the glue.

Is this what your coral cactus looks like? I have never seen flowers glued on to these, but nothing surprises me!

This plant is Euphorbia lactea crest, not a true cactus. They usually are found in stores in a pretty pot with no drainage holes and rocks glued on the top. If that is your situation, please remove the rocks (mine pried off easily with a butter knife) and repot to ensure good drainage.

A search on this forum will provide you with some good info.

Oh - the rocks in this picture are top dressing, not glued.

I've never seen flowers glued onto cacti like these, ... but it's very common on cacti like these ... (those on the left).

The blooming cactus on the right has produced genuine flowers ...

@Crenda - those are lovely crested Euphorbias. I see they are grafted. Understandable for the white one, but I'm curious why the green one is grafted, and what species the bases and grafts are, and what the life expectancy is or whether the grafted parts will grow at the same speed and stay together.

I think these are grafted onto E. neriifolia, but I am not sure. I really don't know if the stock will grow at the same rate. I do know that the crest can grow to be huge with the right conditions. I'm talking 8 foot tall huge, and have only seen those grand old plants in professional gardens.

If they should separate, the crest can be rooted and grown without grafting. Mine are about 3-4 years old now.