Erase Something If I Make a Mistake?

If you make a mistake while painting with the Adjustment Brush, just press-and-hold the Option (PC: Alt) key and paint over the area where you messed up. When you do this (holding that key down), you’re actually swapping over to a different brush that’s set up to erase the mask, and since this is a different brush, it actually has its own separate settings. These settings are found at the bottom of the Adjustment Brush panel, but you can’t access them until you actually make a brush stroke (I know, it’s weird). Once you paint a stroke, you can then click on the word “Erase” down at the bottom of the panel and set your settings for the Erase brush. Again, these Erase settings are only available after you’ve painted a stroke, then you can access them by either: (a) pressing-and-holding the Option key and they toggle as long as you hold that key down, or (b) you can just click the Erase button (as seen above left). Note: You can also erase parts of your Gradient Filter (in case there’s an area you don’t want to be affected by the filter), but it’s different for this tool: click-and-drag your gradient, then you’ll see a Brush button at the top right of its panel (as seen above right)—just click on it and then, once again, press-and-hold the Option key and erase over the areas you don’t want affected.