Here are manual uninstall instructions for the QC/ALM client, depending on the operating system:

For Windows XP client:

1. Clear Common Files
1.1. Open the folders:
1.1.1. c:Program FilesCommon files
1.1.2. %USERPROFILE%Local SettingsApplication DataHP
1.1.3. C:Documents and SettingsAll UsersApplication DataHP
1.2. Delete all folders that might have to do with Quality CenterALM Platform:
1.2.1. Mercury
1.2.2. Mercury Interactive
1.2.3. HP- only if Quality Center folder is under it
1.2.4. ALM-Platform
1.2.5. ALM-Client
2. Clear Temporary folder
2.1. Open the command line
2.2. Write %temp% and click Enter
2.3. Delete all folders that have might to do with Quality Center
2.3.1. Quality Center
2.3.2. Mercury
2.3.3. Mercury Interactive
2.3.4. TD_80
3. Clear Registry- Only on a client machine- not on a server!
3.1. Open the command line
3.2. Write regedit and click Enter
3.3. Navigate to: My ComputerHKEY_LOCAL_MACHINESoftware
3.4. Delete all folder that have to do with Quality Center:
3.4.1. Mercury
3.4.2. Mercury Interactive
4. Clear Loader Class
4.1. Open Explorer
4.2. In the toolbar select Tools -> Internet Options
4.3. In the window that opened navigate to tab General
4.4. Under the section Browsing Settings click the History Button
4.5. In the window that opened click on the button View Objects
4.6. In the window that opened delete all files that:
4.6.1. begin with Loader Class
4.6.2. begin with Spider91
4.6.3. begin with ALM
5. Clear Temporary Internet Files
5.1. Open Internet Explorer
5.2. In the toolbar select Tools -> Internet Options
5.3. In the window that opened navigate to General tab
5.4. Under the section Browsing Settings click the History Button
5.5. In the window that opened click on the button View Files button
5.6. Delete all Temporally Internet Files

For Vista or Windows 7 clients:

1. Clear Common Files
1.1. Open the folders:
1.1.1. c:Program FilesCommon files
1.1.2. %LOCALAPPDATA%HP
1.1.3. %ALLUSERSPROFILE%HP
1.2. Delete all folders that might have to do with Quality CenterALM Platform:
1.2.1. Mercury
1.2.2. Mercury Interactive
1.2.3. HP- only if Quality Center folder is under it
1.2.4. ALM-Platform
1.2.5. ALM-Client
2. Clear Temporary folder
2.1. Open the command line
2.2. Write %temp% and click Enter
2.3. Delete all folder that have might to do with Quality Center
2.3.1. Quality Center
2.3.2. Mercury
2.3.3. Mercury Interactive
2.3.4. TD_80
2.4. Delete the following files:
2.4.1. interop.ALPLoader.dll
2.4.1. interop.ALM-Platform-Loader.11.cab
2.4.3. interop.ALM-Platform-Loader.11.ocx
3. Clear Registry- Only on a client machine- not on a server!
3.1. Open the command line
3.2. Write regedit and click Enter
3.3. Navigate to: My ComputerHKEY_LOCAL_MACHINESoftware
3.4. Delete all folder that have to do with Quality Center:
3.4.1. Mercury
3.4.2. Mercury Interactive
4. Clear Loader Class
4.1. Open Explorer
4.2. In the toolbar select Tools -> Internet Options
4.3. In the window that opened navigate to tab General
4.4. Under the section Browsing Settings click the History Button
4.5. In the window that opened click on the button View Objects
4.6. In the window that opened delete all files that: