How could one remove water from an acid?

Remove water.....

Remove water from an acid??? Water is what makes it an acid. Remove the water and you may no longer have an acid. Heating a solution of hydrochloric acid (or HBr or HI) will produce HCl gas (or HBr gas or HI gas). Boiling an acid will produce some nasty airborne substances which will not make you a happy camper, so don't attempt to simply boiling off the water. These substances will reform the acid when they hit the moisture laden tissue in your nose, mouth and lungs, and you won't like it. It's not like boiling off the water from a solution of a salt, where the solid salt is left behind.

Simplistically, evaporation. That has its problems (in that it concentrates the impurities). Also note that the water used to dilute acids is generally deionized or distilled water.

You could boil it. Boiling point of water is below that of acids, so that would work.

Add a base until the water is neutral.

generally speaking, you cannot. You would have to go back to the creation of the acid via the primary process (often a gas reaction with water), and that isn't by simple evaporation. If you over-dilute, you cannot easily undo. You can only add a more concentrated acid source. Some things are not readily reversible.

Some acids in college labs are concentrated and others are dilute.
In general, concentrating dilute acids is difficult, and the method depends on what kind of acid you start with.

The dilute acids in a college lab are made by the dilution of concentrated acids. There is no need to concentrate them yourself, just go to the stockroom.