There isnt really a way to remove just that command on the receive connector as far as I know.
You have a few options you can test out - but these options will disable all the ESMTP verbs
For the receive connector:
Set this to false
The EnhancedStatusCodesEnabled parameter specifies whether the ENHANCEDSTATUSCODES Extended SMTP extension is enabled or disabled on the Receive connector. Valid values are:
$true: ENHANCEDSTATUSCODES is enabled and is advertised in the EHLO response. This is the default value.
$false: ENHANCEDSTATUSCODES is disabled and isn't advertised in the EHLO response.
For the Send Connector:
The ForceHELO parameter specifies whether HELO is sent instead of the default EHLO. Valid values are $true or $false. The default value is $false.