Warning - When you delete the 'element' you will also delete these elements.
Many elements depend on (need) other elements.
The Delete Dependents dialog is warning to you that, if you want to delete an element, you will also delete one or more other elements.
•Do Delete - click the button
- or -
•Cancel Delete - click the button
When you add a Pin-Joint, you select two Points in two different Parts.
Thus, the Pin-Joint depends on (needs) the two Points. and the two Parts.
If you want to delete one of the Points, you will also delete the Pin-Joint.
If you want to delete one of the Parts, you will also delete the Pin-Joint.