#Delete the selection

Key Del. Removes the selected sketch entities.

#What goes with them

The constraints and dimensions that were held on the deleted geometry: a constraint missing one of its sides cannot work.

So after a delete the degrees of freedom usually go up — you have removed what held the shape. The counter at the bottom shows how many were freed. If the sketch stopped being defined, define it again before building a body on it.

#What stays

Points where other entities meet: they belong to the junction, not to one line. Only what has become nobody's is removed.

#Careful with what already carries a body

If a feature stands on the entity you delete, the feature goes with it. The program asks first and lists by name what else will disappear — read that list, it is the price of the action.

#A common beginner's mistake

Deleting a “spare” line in a defined sketch and finding the part has drifted. The cause is not the deletion but the constraints of neighbouring entities that sat on that line. The degrees-of-freedom counter shows how many were freed.