How to remove ajax toolkit from website

How can i remove the ajax toolkit from my website? i developed my website in .net 4.0 when i compile it in 2.0 and run it, it gets this error on page load.

Could not load file or assembly 'AjaxControlToolkit' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded. 

I thinks its the Ajax that causes me that error because ajax is not present ing .net 2.0

I am not using ajax in my Website so its Okay for me to delete it or remove it from the current website.

EDIT This is the assembly Load Trace:

=== Pre-bind state information ===
LOG: User = PJLIMAIN\aslaure
LOG: DisplayName = AjaxControlToolkit
 (Partial)
LOG: Appbase = file:///C:/Users/aslaure/Desktop/IACS References/PJLhuillier.IACS/PJLhuillier.IACS/
LOG: Initial PrivatePath = C:\Users\aslaure\Desktop\IACS References\PJLhuillier.IACS\PJLhuillier.IACS\bin
Calling assembly : (Unknown).
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\Users\aslaure\Desktop\IACS References\PJLhuillier.IACS\PJLhuillier.IACS\web.config
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v2.0.50727\config\machine.config.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Attempting download of new URL file:///C:/Users/aslaure/AppData/Local/Temp/Temporary ASP.NET Files/root/70cff49e/7a1e4609/AjaxControlToolkit.DLL.
LOG: Attempting download of new URL file:///C:/Users/aslaure/AppData/Local/Temp/Temporary ASP.NET Files/root/70cff49e/7a1e4609/AjaxControlToolkit/AjaxControlToolkit.DLL.
LOG: Attempting download of new URL file:///C:/Users/aslaure/Desktop/IACS References/PJLhuillier.IACS/PJLhuillier.IACS/bin/AjaxControlToolkit.DLL.
ERR: Failed to complete setup of assembly (hr = 0x8013101b). Probing terminated.

You should remove this line from top of aspx file :

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>