If I get you correctly , You have an LDAP integrated user and you deleted the same from unity Connection and then tried to re-import the same from "Import Users" option from Import Page but user is not visible.
Ideally that User should be available for import at Unity Page again , unless it is not marked inactive or deleted from Active Directory.
You can Verify if this User exists in Unity Database Instance(s) using below two admin CLI queries by providing the alias below.
run cuc dbquery unitydirdb select * from vw_user where alias='ProvideAliasofUserhere'
run sql select * from enduser where userid='ProvideAliasofUserhere'
Please follow the troubleshooting guide for further troubleshooting and engage Cisco TAC for further help.