You could use the floor if you don’t have any other surface to iron on. Just be careful with a hot iron around carpeting. This method works to remove vinyl or rubber prints that were heat transferred to the clothing in the first place.
If you don’t have a spare towel handy, you could also use an old t-shirt or anything else that is soft and not prone to damage by heat.
The wet cloth will create a protective layer between the iron and the printing so it doesn’t melt onto the iron.
If the iron is the heavy old-fashioned kind, then you can just let it sit on top of the printing and the weight should be enough on its own.
If you leave the iron on too long after the wet cloth stops fizzing, it could burn.
Be careful to always scrape away from you with the knife to avoid cutting yourself. Try to use the knife to just loosen the edges of the printing, and then peel as much as you can off with your fingers to avoid damaging the fabric below with the knife.
You may have to go over sections several times, depending how stuck on the printing is.
You can also look for special heat transfer vinyl remover that is designed to take vinyl lettering off of clothing. Solvents only work to remove vinyl and rubber prints from clothing. Screen printed ink is permanent on clothes.
If the clothing looks fine after you pour the solvent on, then it is safe to proceed. If not, then you should find another solvent to use so you don’t ruin your clothing. Don’t use solvents on delicate fabrics such as rayon, wool, or silk.
It would probably be easiest to sit or stand at a table or counter as you remove the printing.
Make sure that you are working over a surface that will be easy to clean up if you accidentally spill any solvent. Stretching the fabric out so that the solvent can soak in completely can make the process easier. Just make sure not to stretch the clothing so much that you damage or distort it.
Be careful when you use a knife and always scrape away from you. You can wear latex gloves if you don’t want to get the solvent on your fingers and hands.
If you can’t get it all off with a solvent, then you can try using the heat from an iron to loosen the printing.
If there is any glue residue or stickiness left where the print used to be after you wash the clothing, then try an adhesive remover to get the residue off.
