Unlike sewn-on buttons, which can be removed in seconds with a few scissor snips, the metal rivet-style buttons on jeans are quite difficult to take off. They're designed that way because the waistband button on jeans needs to be hardwearing and extra secure. Removing a jean button, which is often required for tailoring and refashioning projects, is possible with the appropriate tools and techniques. There are two methods to consider: one that cuts through the shank of the button and one that pries the button apart.
Before tacking the task of removing a jean button, it's important to understand how the button is attached to the waistband. Classic metal jean buttons are made of two pieces: the larger button side, which includes a heavy nail or screw, and the smaller rivet side, into which the button side is hammered or screwed. Jean buttons are put in place with a rivet tool or a hammer, which secures the two sides together. The attachment is designed to be permanent, so removing a jean button requires a decent set of tools and some elbow grease.
You should understand that removing a jean button will leave a hole that goes all the way through the waistband of the jeans. If you're replacing the button in the same spot, you can use the same hole to attach the new jean button, but you might need to partially sew it up. If you're putting a button in a different spot on the waistband, you can sew or patch the hole, but expect the repair to be visible.
Cutting a jean button through the post is probably the easiest method for removing the button. It requires one of two specific tools: linesman's pliers, also known as combination pliers, or wire cutters. Linesman's pliers have a flat gripping area at the nose, below which is a beveled, or indented, cutting edge; wire cutters are similar but lack the gripping section. This method destroys the button, so have a replacement ready if needed.
Arrange the jeans so that the inside of the waistband and back rivet of the button is facing you. Carefully slide one of the cutting edges of the pliers or wire cutter under the rivet flush with the fabric of the waistband. Squeeze the handles of the tool together so that the opposite cutting edge slides under the rivet too. Squeeze as hard as is necessary to cut through the post part of the button and then remove the two sides of the button from the waistband.
Instead of cutting a jean button, it's possible to force it apart by gripping each side of the button with a pair of pliers. Use two pairs of pliers, one of a suitable size to tightly grip the button side and another to grip the rivet side. Some jean buttons are screwed together, and others are hammered together, so try both a twisting technique and a pulling technique to figure out which one works.
You might also be able to remove a jean button by holding the button with pliers and pushing the rivet side up with a flathead screwdriver. Use a levering motion and work your way around the rivet, gradually loosening it from the post until you're able to pull the two sides apart.