If you have an Android phone and have downloaded the Google Fit and Walker Tracker app you may have Google Fit turned ON in the Walker Tracker app. If you do not wish to use your phone as your pedometer, then Google Fit will not be your best option.
Open the Walker Tracker app and take a look at whether Google Fit is ON as shown in the picture below:
Move the slider to the left to turn Google Fit off as shown below:
Google Fit will always show as an option to turn on in the Walker Tracker app as long as you have both the Google Fit and Walker Tracker apps on your phone and no other device or app connected. Be careful not to turn on Google Fit accidentally.