Renaming a widget that had a previously connected slot leaves ghost slot and cannot compile now

• I originally had the checkbox named “Checkbox_2”. 
• I selected “Go to Slot…” for the variable Checkbox_2 which created a slot for Checkbox_2
• I renamed Checkbox_2 to “CheckallCB”
• The slot function was broken and I couldn’t just rename the function
• I needed to right click the new CheckallCB and select “Go to Slot..” just to generate the right function again versus just renaming
•  Checkbox_2 slot still exists in the code as a ghost slot and won't compile now 

moc_mainwindow.obj:-1: error: LNK2019: unresolved external symbol "private: void __cdecl MainWindow::on_checkBox_2_stateChanged(int)" (?on_checkBox_2_stateChanged@MainWindow@@AEAAXH@Z) referenced in function "private: static void __cdecl MainWindow::qt_static_metacall(class QObject *,enum QMetaObject::Call,int,void * *)" (?qt_static_metacall@MainWindow@@CAXPEAVQObject@@W4Call@QMetaObject@@HPEAPEAX@Z)