Deleting user dictionary

https://helpx.adobe.com/indesign/using/spell-checking-language-dictionaries.html

Remove, relink, and reorder user dictionaries
Choose Edit > Preferences > Dictionary (Windows) or InDesign > Preferences > Dictionary (Mac OS).
From the Language menu, choose the language to which the dictionary belongs.
Do any of the following:
To remove a dictionary from the list, select it and click the Remove User Dictionary icon . You must have at least one dictionary per language.

If the language dictionary includes a question mark icon next to it, select the dictionary, click the Relink User Dictionary icon, and then locate and open the user dictionary.

To change the order of the user dictionaries, drag them. The order of the dictionaries in the list is the order in which the dictionaries are checked.