When you place a label, that label can be linked to an element, or placed as an independent element. This is important, since dragging a copy of a linked label creates a label that is also linked to that content. Independ
In the above example, the redundant labels were created by dragging a copy of the first label to create new labels. The result is that when the fill is deleted, all labels are lost.
One method for preventing this is to copy/paste, rather than dragging a copy, to create new labels that are not linked or associated to model or drawing elements. These can be moved to the side, then cleaned up and repositioned after the necessary drawing elements are deleted.
Another option is to select the labels (or all labels in a view), then right click and choose Convert to Independent Label.
A fair warning on independent labels; they will not reposition with any content. They can only be text labels, and they can not be converted to any other label type, since there is no way to associate them to drafting or model elements without deleting and replacing.
The label tool has a lot of options, and a lot of benefits to having links to content, but when you need an independent text label, just know there are ways to fix a drag and copy mistake.