Please elaborate if you want to remove duplicate records from a standard object’s field or something else. In Case of prior one you can remove those from anonymous window.
For Example:
List<Account> listOfAccounts = [Select Id, name From Account limit 200];
Set<String> accountSet = new Set<String>();
List<Account> listOfDuplicateNames = new List<Account>();
for(Account acc : listOfAccounts){
if(accountSet.contains(acc.name)){
listOfDuplicateNames.add(acc);
}
else {
accountSet.add(acc.name);
}
}
delete listOfDuplicateNames;