Regarding your query, could you please follow our guide and two steps below?
Step 1: Connect via SSH to your magneto installation and execute below commands
php bin/magento module:disable Bss_PreviousNextProduct –clear-static-content; php bin/magento setup:upgrade
Step 2: Remove extension files
cd app/code/Bss/ rm -rf PreviousNextProduct
If your site is developer mode, please follow 2 steps.
If your site is production mode, please follow 2 steps and run command deploy as well.
If you need any further assistance, please feel free to contact us via email firstname.lastname@example.org