Remove an item from a LIST using PartiQL and DynamoDB

Question

Trying to remove an item from a list in DynamoDB using PartiQL and parameters.

This works with no problem

update table name REMOVE members[1] 
SET log=?
WHERE PK=? AND SK=?

but if I use a parameter for the list index - members[?] - then I get the following error 'Execute PartiQL statement failed: Validation Error: Statement wasn't well formed, can't be processed: Invalid path component for simple path'

update table name REMOVE members[?] 
SET log=?
WHERE PK=? AND SK=?