In the attached file:
1. Open the sketch in Sketcher WB
2. Scroll down to constraint labelled "UpperGuideSlopLines"
3. Click on it and notice where the two constraint texts are
4. On the right hand constraint, note the "UprRtSlopInLineWithUprRtGuide" constraint label above it
5. Click the "UpperGuideSlopLines" check box to hide it
Result: The right hand constraint label disappears, but not the left; the additional constraint above it disappears
OS: FreeBSD 11.3-RELEASE-p6
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.0.18.4
Build type: Release
Python version: 3.7.6
Qt version: 5.13.2
Coin version: 3.1.3
OCC version: 7.4.0.beta
Locale: C/Default (C)