There may come a time when your site is not working properly and it could be due to a couple of plugins deciding to fight in the background! In order to rule that out and begin the process of determining which of your plugins is the culprit, you may need to disable all of your plugins without access to your wp-admin area.
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SFTP
This section does assume that you've already reviewed the SFTP article and understand how to use it.
To start off, you're going connect to your website using your FTP client. Once connected, you need to navigate to the web/content/wp-content/ folder. Inside the wp-content folder, you will find a folder called plugins. This is where WordPress stores all of the plugins installed on your website. You will then want to right click on the plugins folder and select Rename.
Change the name of the plugins folder to anything other than plugins. In our example, we will call it plugins.disabled. Once you do this, all of your plugins will be deactivated. If the issue was with your plugins, then doing this should allow you to log into your WordPress admin area.
Once you're in, go back to your /wp-content/ folder and rename plugins.disabled back to plugins. Now you will want to track down that culprit. You can do that by activating one plugin at a time until your site breaks again. Once it breaks, you will know exactly which plugin is doing the rabble-rousing.
phpMyAdmin
This section does assume that you've already reviewed the phpMyAdmin article and understand how to use it.
You can also go into your phpMyAdmin and update the database's options table to disable all of your plugins. To do this, access your phpMyAdmin, select your database and then click on the options table. (As you can see that all tables in the database have the wp_ prefix before the table name. Your tables may have a different prefix.)
From here, you will click on the wp_options table. Inside the wp_options table, you will see rows of different options. You will need to find the option active_plugins and then click on the Edit Link.
On the next screen, you will need to change the option_value field to a:0:{}
Then save your changes by clicking Go. Now all of your plugins have been deactivated.
From here you should check your site to see if whatever wasn't working has been corrected. If you're able to gain access to your wp-admin area, you can begin reactivating your plugins one at a time until your site breaks again. Once it breaks, you will know exactly which plugin is causing the issues.