Hi SharonRoffey,
As per your description, I know you already tried Select All > Objects in the Editing group under Home tab, but you are still unable to find text bob in your Word document.
First, please make sure you are viewing your document in Print Layout view. If you are viewing your document in some other view, then you won't be able to see some of your graphics, including text boxes.
If the text box is still not visible, then you should check to make sure that the display of drawings hasn't been turned off. Follow these steps:
1.Open problematic Word document, click the File >click Options
- Click Advanced at the left side of the dialog box.
- Scroll through the options until you can see the Show Document Content section.

4.Make sure the Show Picture Placeholders check box is cleared.
5.Make sure the Show Drawings and Text Boxes on Screen check box is selected.
6.Click on OK.
Provided you are still viewing the document in Print Layout view, you should be able to see any text boxes. If you still can't see it, it could be possible that the text box is formatted for no line and no fill and that the text it contains is formatted as hidden. If you suspect this is the case, try to Zoom out on your page so that you can see it all on the screen. Then you click Select> Select Objects. Click and drag to create a selection box around the entire page. When you release the mouse button, any objects on the page should be selected. You can then delete them.
If you are still having problems locating and getting rid of the text box, you can try a macro approach. The following macro will step through all the shapes defined in the document and delete them. This is a great approach if the offending text box is the only shape in your entire document.

If you can't sort it out, and if it is convenient for you, could you please send me a copy of the document file so that I can take a look from my side, and I will investigate the issue and help you to check Fix it.?
If there is confidential information, then you can send it to me in Private Message
I appreciate your understanding and stay safe!!
Best Regards
Waqas Muhammad