Looking briefly through the code I noticed some typos.
1. I attached one annoying one regarding username. Apart from the typo "charactor" and "username only accept" issue, it looks very weird and confusing also. It should be clearer such as:
"Username can contain letters, digits or undescore and the first letter must not be a digit!"
2. "Are you sure you do want to remove selected user?" -> "Are you sure you want to remove the selected user?" (same goes for the plural)
3. "You've choose 'PUBLIC' or 'DBA', those users can't be droped. Are you sure you do want to remove selected user except 'PUBLIC' or 'DBA'?"
"You have selected 'PUBLIC' or 'DBA', but those users cannot be dropped. Are you sure you want to remove the other users?" (Same goes for the singular scenario with "user" instead of "users" in the question)
Also, when creating/editing an user the "Success!" message should be clearer (instead of just displaying "Success").
"Remove selected users success!" should be "Selected users have been removed!" or something along that sort.
4. "Password length at least 4!" -> "Password should contain at least 4 characters". A standard is to mention something like: "Your password must be 6 to 32 characters long". In this case it would be 4 to 31.