I've run into this many times and have never figured it out. Often times when you place geometry in a sketch it applies contraints automagically. Often times however if I want to get rid of these constraints they don't show up at least I can't find them to delete them.
For instance in the part below the diameter is constrained to the origin. That constraint was put in because I picked the center of the other circle or origin point. However when I select the circle or the center point etc etc no constraint exists that I can delete so I can move the circle. How does one get to this constraint or where is it?
Outer circle shows on edge, no other constraints show up.
Selecting just the point shows no relationships
Selecting the inner diameter only shows the diameter dim relationship
Selecting the outer edge only shows on edge
Clearly the center point of the inner circle has a relationship to either the origin or the center point of the other circle...but I can't find it anywhere.
Historically I would just delete the circle and draw one off center...but I thought I'd try and figure out what I'm missing here.
EDIT TO ADD: I know the constraint is there because if I LMB click the center point and hold the button down and move off the center point the Coincident relationship symbol shows up in yellow....I can't get to it to delete though.