In physics or math, when you rescale a quantity to 1 you are normalizing it.
This might come up if you are finding a unit vector, for instance.
The term is also used when talking about natural units -- the idea of adjusting your system of units such that certain physical constants (such as the speed of light) are equal to one. From wikipedia:
A purely natural system of units is defined in such a way that some set of selected universal physical constants are each normalized to unity; that is, their numerical values in terms of these units are exactly 1.
You can normalize things to other than 1, but 1 is kind of the "default" I'd assume on seeing the word without context.
You probably wouldn't use this if you're just initializing a value to 1 in a computer program. If 1 is the natural default value for e.g. a counter, you would probably just use the word initializing, though.
The question is ambiguous enough that I can't tell which (if either) word is more appropriate.