From Xojo Documentation

Property (As Boolean )
aiOSLayoutConstraint.Active = newBooleanValue
BooleanValue = aiOSLayoutConstraint.Active

Supported on Mobile (iOS).

Indicates if this auto-layout rule is active.

Sample Code

De-activate an existing named constraint:

// "TAWidth" is a width constraint for a TextField that has been given
// a name in the auto-layout Inspector properties.
Dim c As iOSLayoutConstraint = Self.Constraint("TAWidth")
c.Active = False