Can my employer take my pay to less than what I was hired at?

Yes, your pay can be reduced at any time as long as the employer is complying with wage and hour law.  For example, if you were hired at $15.00 per hour, you employer could later reduce that to $10.00 per hour whether you agreed with that or not. However, if the employer could not reduce it to $5.00 per hour because that is below minimum wage.