To submit your dormant accounts you can click on this link. Alternatively you can also follow the navigation as shown below.
Navigation: Accounts Production >> Choose the client >> Settings >> Report Settings >> Company Info >> Edit
Once you navigate to the page change the trading status as Dormant and then you may proceed further to prepare the Accounts Report.
Once the Accounts report is created, you can follow the next step to submit your accounts. This can be done by following the below navigation.
Navigation: Tasks >> Submit >> Click on + Submit Accounts >> Choose the Accounts Report and then click on Submit to Companies House from the Accounts Production Module.
Please refer below screenshot for more help.