Toolbar : 
Geometry Toolbar 

Menu : 
Add menu > Geometry submenu> > MergePoints 

Use Merge Point to merge two Points to one Point. 'Mergepoints' for:
Add Coincident Constraints for construction geometry See also: sketchpath, Add Coincident Constraint. 

Notes:

Before 
After 
Select: 
In SelectionWindow & GeometryTree 


Click a Point and then a different Point. One Point is deleted (Compare with CoincidentPtoP), and the sketchelements move together. 
A Point PointN 

A Point and the Coincident constraint is deleted 
A Point PointN 


A Point – rather than two See sketchloops. 