Hi Peter,
Thank you for your purchase.

It is possible to hide Add new entry button and that way users won't be able to add a new record.
If you are skillful with CSS you can do it by yourself , if not I can do it for you.

Hi Peter,

You can add this code on page in Text field that you don't want "New" button to be visible.

<style>
a.dt-button.new_table_entry.DTTT_button.DTTT_button_new {
    display: none !important;
}
</style>;

If you have any doubts please provide me temporary WP admin login credentials so I can do it for you.
You can write credentials here but please check Private reply so nobody can see it except us.