Short answer is
Yes, you can be removed from your position as Shop NCOIC without a relief for cause report. All that is necessary is that Leadership loses confidence in you and decides to put someone else in charge. They should counsel you as to why you were removed. Based on the information you provided I would assume they have not counseled you as to why you were removed. I am assuming they see your enrollment in the ABCP as a failure to meet a standard and as such chose to remove you as you did not meet the standard for weight control.
1% Over BodyFat
With regard to 1% over and the enrollment in the ABCP. 1% is relatively small and can typically be loss quickly. The key questions here are:
1. where you taped correctly?
2. Did they do at least two tapes by two different people? Meaning another person verified the accuracy of the tape by doing it a second time. While not required by AR 600-9 it was an action I initiated before placing an individual on the ABCP as I did not want to inaccurately place a Soldier in the ABCP for an inaccurate measurement.