Knock it out with tranq arrows/tranq darts.

Choose your smoothing balm

1.minor smoothing balm you can tame it with this but it's way slower put a sleeping bag and sleep make sure you brought lots of narcotics 170 will be enough just in case craft more if you need.

2.using major smoothing balm will do it a lot faster

You can tame him pretty quick

you watch vids(videos) on YouTube for more information search in "how to tame Theizinosaurus"

More Therizinosaurus Taming & KO Tips