I'm on Jetbrains but same thing, it is extremely frustrating that there is no control over the completions.
Right now it's not possible, you need to either take it all or write it yourself as before.
The reason for Github/Microsoft doing that with CoPilot is quite simple: Their #1 marketing strategy is how much more "efficient" their users are.
They say 60% of the code is written by CoPilot.
What they do not say or track is that of those 60% users likely delete 95% afterward.
In reality accepting a solution only means that you need a fraction of it, often it's wrong redundant and a multiple of what you want. But that would destroy their metrics.
I'd recommend making a bug report to the plugin developer and hope that enough people do it until it's fixed.
The other option is to hack the plugin itself, I looked into that and it can be done. Though I'm not too fond of that approach.