Removing created items not possible ("delete" button inactive)

[DarkTrick]

System: XUbuntu 19.04
package in question: menulibre
Version of package in question: 2.2.0-2

Problem 1:
 Some items are not removable with menulibre. I can reconfigure (e.g. rename) them, but removing is not possible.
 I cannot specify the circumstances precisely. I *can* say, that even items I created myself are sometimes not removable.

Problem 2:
 It is not possible to start menulibre as root (via sudo). If "Problem 1" is a priviledge problem, it cannot be solved using sudo.

Some apps I CANNOT remove
"run program..." (app finder)
"About Xfce"
"Python"
"Visual Studio Code"
"Bless Hex Editor"
"Fritzing"
"Libre Office"
GIMP
"nomacs"

Some apps I CAN remove:
"Giggle"
"Arduino"
"Anki"

[DarkTrick (darktrick1337)]

Additional information:
 The "delete" button is inactive / greyed out.