When you create webforms using Zoho CRM, you have an option to hide any field except the ones marked as required fields.

To hide a multi-select picklist field in a webform, follow these steps:

1. Go to Setup > Developer Space > Webforms.

2. Select the web form you want to edit and in the WYSIWYG Editor, drag and drop the desired picklist field. Let's say there is a field here called Lead's Interest.

3. Click the field's Settings icon.

4. Select the Mark as Hidden Field checkbox and select a default value. Click Done.

5. Once the form is published, your website visitor will not be able to see this picklist field.