Gravity Forms entry-related data is stored in three tables. If your WordPress database prefix is wp_, these are the tables:
wp_gf_entry
wp_gf_entry_meta
wp_gf_entry_notes
If you have deleted all the entries, you should have no records in any of those tables.
The autoincrement for the entry ID is on the wp_gf_entry table. You can find out what that is currently using this SQL:
SHOW TABLE STATUS LIKE 'wp_gf_entry';
That shows a bunch of columns, one of which is Auto_increment.
To reset that, first, please make a database backup, in case something goes horribly wrong. This worked for me with my MySQL database installation and version, but your may be different. Please make a database backup first.
To reset the auto_increment for the wp_gf_entry, this is the SQL command to execute:
ALTER TABLE wp_gf_entry AUTO_INCREMENT = 1;
Then run the previous command SHOW TABLE STATUS LIKE 'wp_gf_entry'; to check to see the new auto_increment value.
That showed “1” for me, so that worked, and the next entry that will be stored with one of your forms will get the entry ID 1.
Like I mentioned, make a database backup first. We can’t be held responsible for anything which may go wrong here. Let us know how it turns out.
Disclaimer : Third party plugins or code snippets that are provided or referenced by our Support Team or documentation, are provided as suggestions only. We do not evaluate, test, guarantee or officially support third party solutions or code-snippets. You are wholly responsible for determining if any suggestion or code snippet provided is sufficient to meet the functional, security, legal, ongoing cost and support needs of your project, as well as testing and confirming performance across future product updates.