Moving scrum events to do or not to do?

What is going on in the PO"s working day that they believe to be more urgent and of greater priority?

An impediment to effective product ownership is being exposed. The first thing to do is to establish transparency over what that impediment is. The PO may just be reflecting the organization's culture back upwards for example, with no sense of urgency for agile change being communicated or reinforced.

He is also a owner and busy with lots of different things like interviewing new candidates, making presentations for different grands, and stake and share holders. and a ux designer of the team. we have a small company which limited resources. The team should work agile and make meters but the PO is too busy to be available so the team needs to work around his schedule.

Perhaps one of the things that he should be doing is interviewing new candidates to become the Product Owner and/or UX designer for the team.

If he can't make things like the Sprint Retrospective, how is he participating in things like Product Backlog refinement and making sure that the Developers understand what the stakeholders need or participating in the Sprint Review to plan the next steps?

This is a good example of an X-Y problem. The solutions to be discussed are not about the scheduling of the events, but the focus and availability of the person in the role of Product Owner.

So this individual is the business owner, Product Owner, and UX Designer. It also sounds like he is the Sales, Marketing and strategist. I'll bet there are other job positions he is also covering. He may want the team to work in an agile fashion but probably because he misunderstands the benefits.  He doesn't seem to understand that the way a company is organized and the responsibilities are distributed makes a huge impact on a company's ability to be agile. 

As a Scrum Master, it might be worth your time to help him understand the Scrum framework better.  Educate him on what it means for a company to be agile.  But first make sure you understand it well. Scrum is a framework that helps organizations adapt to complex changing environments using empirical methods.  Being agile means that the entity is able to quickly adapt to changes in the environment.  Share the Evidence Based Management Guide that is found here on this site with him. Aid him in understanding how he can better organize and staff the company to make the agile dream a reality.

my product owner constantly wants the scrum events (retro and/or planning session) to be moved to a different day

Non availability of the PO is an issue to be addressed. You should have a chat with him. The scrum guide says that the PO can delegate his responsibility to someone but the accountability lies with the PO. It would be worthwhile to explore if there is someone to whom the PO can delegate his responsibility so that this person can attend your ceremonies in the absence of the PO. However this individual needs to be empowered by the PO else decision making will be delayed if he needs to check with the PO and then come back to the team.