This error will come if you would have tried to install many themes. Installing many themes is not a problem, but installing many themes at the same time might be the problem.
Go to the wp-content/themes and uninstall the themes simply by renaming the files or removing the files.
You can use cpanel or filezilla to do the same.
Note: 1. For safety purpose have the backup of your website first.
2. If you have loss any data, ngdeveloper.com will not take any responsibility.
Thanks for reading this post………….!!!
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