Remove Character at Specific Location in String

In the post Remove the Trailing Character From a String Using SQL, we use substr SQL function. To remove a character at a specific location in a string, I create a function that takes advantage of substr again as shown below.

create or replace function remove_at(
   str IN varchar2,
   pos IN number)
return varchar2
is
begin
return substr(str,1,pos-1)||substr(str, pos+1, length(str));
end;
/

Now, I apply this function using different locations and the results look correct.

SQL> select id, val from tbl_val;

     ID VAL
------- --------------------------------
      1 abcdef
SQL> select id, remove_at(val,3) val from tbl_val;

     ID VAL
------- --------------------------------
      1 abdef

SQL> select id, remove_at(val,5) val from tbl_val;

     ID VAL
------- --------------------------------
      1 abcdf

SQL> select id, remove_at(val,1) val from tbl_val;

     ID VAL
------- --------------------------------
      1 bcdef

SQL> select id, remove_at(val,0) val from tbl_val;

     ID VAL
------- --------------------------------
      1 abcdef

SQL> select id, remove_at(val,10) val from tbl_val;

     ID VAL
------- --------------------------------
      1 abcdef