If you want to remove Magento extension manually, follow the steps below:
1- Disable the module from /app/etc/modules/.xml
set <active>true</active> to <active>false</active>
2- If their is any dependent my sql table, Remove tables.
3- In Database, Remove resource config record for the respective module from core_resource.
4- Remove the <project_root>/var/cache folder
5- Refresh you home page or any other page.
And it should be Good.