Hi @Chriska! The method you are referring to in your example was called emp in versions of QIIME 2 prior to 2017.2, but was split into two methods (emp-single, emp-paired) for the 2017.2 release.
I think you might have a version mismatch, it looks like you are referring to the "Moving Pictures" tutorial in the docs for 2.0.6, but you are running QIIME 2 2017.2 locally. Please take a look at the "Moving Pictures" tutorial for 2017.2 to see the current version of that tutorial.
There is a version picker in the upper left corner of the docs that let you toggle between versions, if you want:
If you want to see the demux methods for those two versions of QIIME 2, please see the following links:
If you want to learn more about what version of QIIME 2 (and it's plugins) you have installed, please run the following:
$ qiime info
If I misunderstood your comment and you are running a version other than 2017.2, please see the Upgrade/Updating doc for info on getting the latest version of QIIME 2. While we are in alpha development we only support the latest version of QIIME 2.