Removing the percent sign is one of the example cases discussed here: https://www.jmp.com/support/help/14-2/numeric-formats.shtml
Excerpted:
"Enables you to define a custom format for a numeric column. Select Custom, click Set Custom Format, and define the format in the Formula Editor window. For example, if you don’t want to display the percentage sign next to a number, select this option and multiply the number by 100. This is an alternative to selecting the Percent format."
By default, the formula will come up as "value" - this is a variable that is created to represent the axis values. You can use numeric transformations of any kind, or you can convert to a string and add units or other styling to the labels. When the editor comes up, you can use the dialog buttons to add "*" and enter "100", or you can just double-click on the "value" and change the expression to ":value * 100"
