Go to your Google Account: https://myaccount.google.com/
Sign in if needed
Click Data & privacy
Under History settings, click Web & App Activity
Click Manage all Web & App Activity
Click Delete
Choose Delete today, Delete custom range, or Delete all time
Confirm by clicking Delete
To stop future search history saving, turn off Web & App Activity
If you want to delete searches from the Google app or browser history, clear your browser history separately
On Chrome, open History
Click Clear browsing data
Select Browsing history
Click Clear data