Real Life Name Changes:
1) Your Oregon County Circuit Court is the best place to begin if you need or want to make an actual name change. Many have name-change forms online or for sale at the Courthouse.
2) For example, in Washington County, visit the Washington County Circuit Court webpage on Name Change for forms and information.
3) The Oregon State Bar has information on the name change process.
Do you need a Checklist of all those places and people you need to contact when you change your name? There are a lot of Name Change Checklists on the web. But figure out if you want wedding, divorce, or other type of name-change situations, though there is obviously some overlap. Try search words: name change checklist divorce (or wedding or marriage)
Fictional Name Changes, or variations on the theme:
If you are just contemplating the idea of a name change (recreating yourself or creating a fictional character, maybe?), there are other places to visit and books to read, though don’t skip the real life ones mentioned above, assuming you want to go for verisimilitude in your prose:
How to Disappear Completely (book)
If you’d rather have your character fake a disappearance rather than changing a name, consider how people (and fictional characters) through the ages have experimented with pseudocide.