It's easy to remove or hide the table of contents. In fact, you have the option to hide it from a particular report or remove it from all of your reports.
1) How to remove the table of contents from a report
To remove the table of contents from a report simply uncheck the corresponding tick in the Include column within the Report Builder.
2) How to remove the table of contents from all of your reports
To hide the table of contents from all of your reports click on the customisation icon from your main dashboard. You'll then be taken to the customisation dashboard where you should click on Report Content Manager.
Select the Report Type and then Table of Contents from the section drop down menu and uncheck the ticks in the show column to hide the two snippets that make up this section.
That's it you're done, a table of contents will no longer be included in any reports you (or your users) create in the future.