You can delete them if you wish. Here is how. Go to your visit log. On the right there should be an option to "Edit Visit" your visit. Select this option. After a set period of time has passed you can't really edit but the page does give you the opportunity to delete.
You would need to archive each of your visits individually. There is no need to do so if it is a bother.
Before you do delet
check out this thread to see if you want to retain your visits or not and decide if you feel there is a valid reason to keep visiting your own creations. Basically, if you choose to visit it is fine, if you choose not to visit it is fine and if you choose to do a mixture well I suppose that would be fine as well.
I archived all of my creation visits after it became a hassle for me to make new visits. I found that I have said all I want to say in the waymark creation process. I did leave a few notes that had interesting personal visit information that was not appropriate for the waymark itself but there weren't a lot of those.
I am now toying with the idea of creating visits for locations I visit after the initial creation of the waymark. That should really confuse folks.