Here is the official documentation. This is also automatically downloaded at step 2.
Below is a really simple way to do it and I've successfully built my app using .NET framework 4.6.1
Install ILMerge nuget package either via gui or commandline:
Install-Package ilmerge
Verify you have downloaded it. Now Install (not sure the command for this, but just go to your nuget packages):
Note: You probably only need to install it for one of your solutions if you have multiple
Navigate to your solution folder and in the packages folder you should see 'ILMerge' with an executable:
\FindMyiPhone-master\FindMyiPhone-master\packages\ILMerge.2.14.1208\tools
Now here is the executable which you could copy over to your \bin\Debug
(or whereever your app is built) and then in commandline/powershell do something like below:
ILMerge.exe myExecutable.exe myDll1.dll myDll2.dll myDlln.dll myNEWExecutable.exe
You will now have a new executable with all your libraries in one!