Notation Edit mode first by cliciking the "grid" icon.

RightClick on the note where the slur starts, select "Notation Symbols" then select,
"Slur..." -- In the Notation Event window that opens, the lower lefthand option "OK - Rmove Event" will delete a slur.

i don't think we have control over the camber of a slur, it is automatically chosen as regards the direction of the notehead.


--Mac