Photoshop Magic eraser not working properly

@Ray_Sweeting wrong with what?

There are so few situations in which the Magic Eraser tool does anything useful that, like @Kevin Stohlmeyer, I tell people to just avoid it completely because it is almost certainly the wrong tool for the job. In fact, any eraser is the wrong tool for almost any job.

Best practice is: Select first, then mask out what you want to hide. It is better to use a mask because masking is non-destructive and is reversible after the fact. Non-destructive workflows allow you to go back and change or undo the action later, even if you've closed the file in the meantime, so modern practice is to use them whenever possible.

There are many ways to select and mask in Photoshop, ranging from "quick and dirty" (the Magic Wand) to magical (Select Subject) to highly nuanced (channel masks). Which will work best depends on the image and what you're trying to achieve. If you're serious about Photoshop, Katrin Eisman's excellent Photoshop Masking and Compositing should be on your bookshelf.

https://helpx.adobe.com/photoshop/using/erasing-parts-image.html

Hi @Ray_Sweeting that is how the Magic Eraser works - it selects based on color and deletes in one move. You've never gotten a selection preview prior which is why I always teach my students to not use it. Here is what I recommend - If you are looking to preview a selection first before deleting - use the Magic Wand tool. It makes the selection based on color but does not delete until you act on it.