This can be done with the help of
Substring in-built method ,it takes 3 arguments as:-
Syntax:- Substring(string_expression,start_position,string_length);
For Example:- Declare @strvar as Varchar(1000) = 'Vishal,Kumar,0123456789,';
Select Substring(@strvar,1,len(@strvar)-1) as 'Remove_Last_characters'
Output:-
Vishal,Kumar,0123456789