By default, Word encloses the table of contents in a so-called content control, if you insert your TOC via the predefined formats at References | Table of Contents. To get a TOC without a content control, use References | Table of Contents | Custom Table of Contents.

And to delete an existing TOC content control, you can select the whole TOC including the preceding and following paragraph and then press the Delete key.

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional