WordPress Tutorial: In simple steps, going to show you how to deactivate wordpress plugin without login or dashboard access. The following technique can be applied by FTP or Web Server.
Step 1: Login to web server cPanel or connect through FTP
Step 2: Go to WordPress root directory
Step 3: Go to wp-content > plugins folder
Step 4: Select the plugin folder and change the name.
Step 5: Plugin will deactivate and you are done.