How do I clear the parameters?

Before I was using
.commandtext="select * from users where username=?"
.parameters.refresh
.parameters(0)=value

However, this does not work on Oracle.

So I tried to use the parameter.add
But when I come to the second statement the parameter still live in my connection object. I need to clear it. There is no delet method and setting
the name property doesn't work



I don't not want to recreate the command object each time...


Thanks