Delete by condition

How define condition, if I want delete file in Unistaller only when exist other file i other location?

Is it some simple way, plase?

Use IfFileExists, or the easier LogicLib's ${FileExists}.

!include LogicLib.nsh

#...

${If} ${FileExists} $WINDIR\some.dll

  Delete $INSTDIR\some.exe

${EndIf}