There are two primary ways to work in the "Model" environment; parametrically, which focuses on the relationships between features, or directly, which deals only with selected model faces. The main difference is that "Direct Modeling" functions by manipulating faces without regard for previously established relationships.
There are quite a lot of articles on such topic on internet. I just picked two of them:
http://www.engineering.com/tutorials/turning-off-caption-design-history-in-autodesk-fusion-360/
https://www.youtube.com/watch?v=YJU4avXux2s
There is a switch in [Capture Design History] of the context menu of root node of the browser pane.
With API, the corresponding object is adsk.fusion.DesignTypes.
def toogleCaptureHistory(isEnabled):
app = adsk.core.Application.get()
des = adsk.fusion.Design.cast(app.activeProduct)
if isEnabled:
des.designType = adsk.fusion.DesignTypes.ParametricDesignType
else:
des.designType = adsk.fusion.DesignTypes.DirectDesignType