Informatica

Hello, I deleted every file of oracle xe 11g but it still exists in services. I am not able to delete them in full. I tried to install it back but it says there is already such file exist and it cannot run again. Please help. Thanks.

CPU: Intel Pentium G3220 3.0GHz MB: Asus H81M-K RAM: 2GB DDR3 1333 MHz GPU: Intel HD Graphicks HDD: 500GB OS: Windows 7 32bit MONITOR: 1920x1080p 60Hz (VGA) I have some lags when im watching some youtube videos,movies...when opening some page on inthernet,especially videos i need to wait 5-10s...