After completing the evaluation, how to predict PTM lysine or any other modification with unlabeled data for making a web server?
Interesting application. I would suggest using Python's Flask system, which is described in a few pages in O'Reilly's Programming PyTorch, chapter 8. PyTorch in Production. Django is not really recommended (don't say that on Stackoverflow however). O'Reilly do an entire book on Flask, but thats to make the site pretty.

Obviously, the explanation here is Deep Learning rather than ML but the basic gist will hold. You should also think about building a docker for distribution which is easy (same chapter). We're in lockdown so I don't have this book with me. 

The difficult part will be web architecture because you shouldn't have the CPU/GPU on the same server as the quiry interface, otherwise you are prone to a denial of service attack or just sytem overload. To do this you need to consider  Representational state transfer (RESTful) and that is not easy at all (at least for me). Flask facilitates RESTful, but thats like systems admin stuff. I guess before getting into RESTful I'd see how popular your website is, but if its the same server as your institute website you'd need to be really careful because an external user could bring your institutional website down (you wouldn't be popular).