using inno setup uninstall default icon

If you set SetupIconFile then the Uninstall Exe File (e.g. unins000.exe) will have exactly same icon implemented. One way to override displaying of this icon is setting custom UninstallDisplayIcon in [Setup] section for Control Panel Add/Remove list and IconFileName in [Icons] section for shortcuts placed on Desktop, Start Menu, etc. In both cases you have to have your custom Icon file which has to be installed with your app.

[Setup]
SetupIconFile=C:\mysourcedir\mysetup.ico
UninstallDisplayIcon={app}\myuninstall.ico 
                        //overrides icon on Add/Remove List in Control Panel

[Files]
Source: "C:\mysourcedir\myuninstall.ico"; DestDir: "{app}"

[Icons]
Name: "{group}\{cm:UninstallProgram,{#MyAppName}}"; Filename: "{uninstallexe}";
 IconFilename: "{app}\myuninstall.ico" 
                       //overrides icon in Start Menu shortcut

The second one is to have precompiled unins000.exe with specific icon implemented. It can be tricky though in some cases (multiple install with unins001, unins002, etc.; custom code features)

http://stackoverflow.com/questions/15845226/using-inno-setup-uninstall-default-icon