The enthalpy change of a chemical reaction
I found the mass of the empty calorimeter to be: 11.600g, Initial temp in the calorimeter was: 21.00 degrees celcuis, max. temp in the calorimeter from the reaction was: 29.27 degrees celcuis. I can't calculate delta T as Tmaximun-Tinitial

I don't quite understand your issue. I find it strange you can't do the subtraction, so that means I am not understanding something in your question...

In that equation, if I am understanding your question correctly, delta T refers to change in temperature; so it is just one variable you need to enter into the equation, which is 8.27 kelvin or Celsius because they are both the same, 1 for 1.

Obviously T initial is 21.0 degrees and T maximum is 29.27 degrees. So delta T is just the change in temp = 8.27 C.

Hope that helps, and that I am on the same path of thought as you.