Following Kevin Yanks book. How do I uninstall PHP?

I would like to apologise for my ignorance.

I’m wanting to uninstall my current version of PHP and try instead to use an earlier version.

This is because I am getting this error:
Warning: mysqli_connect() [function.mysqli-connect]: Headers and client library minor version mismatch. Headers:50051 Library:50145 in C:\Program Files\Apache Software Foundation\Apache2.2\htdocs\index.php on line 2

How would I go about removing the version of PHP I have now?

Thank you. Sorry for bothering with what must be elementary questions.

whats having both of them…
any way someday you will have to upgrade…
so may be when installing older version you can choose another folder…

Windows installation? or Linux?


So is it right that I don’t have to uninstall any version of PHP is I just update Apache to look at the version I want it to use?