the screen capture about the MODES of this calculators. DEG,RAD, and GRAD remind the user that the angle units in trigonometric function calculations and coordinate conversions are in degrees, radians or grads. They have nothing to do with the other calculations you are doing.
You can only remove DEG by changing the angle unit to RADians or GRADs. In so doing, the new unit indicator (RAD, GRAD) will be displayed instead. There is no point worrying about the angle unit indicator unless you are performing coordinate conversions or calculating trigonometric functions or the inverse trigonometric functions.
MODE 9 cancels the FIX display format: decimal are displayed with a fixed number of decimal places (set by the user). After this key sequence the decimal display format reverts to NORM(al).