Your linear units (XY) are metres. You do not need to change the Z factor as your elevation values should also be in metres. If for some reason your elevation values are in feet, you would use a z-factor of 0.3048 to convert your elevation from feet to meters (1 foot = 0.3048 meters).
Ignore below (It's only relevant if your linear units are in degrees).
See this thread: Z factor in slope tool and these articles: Setting the Z Factor parameter correctly and Determining a Z-factor for scaling linear elevation units to match geographic coordinate values.