How to delete rows from arrays of arrays (Nested CDTs)?

Please find the below screenshot for better understanding on how we are using arrays of arrays.

{
'type!{urn:com:appian:types:CTRIS}CTRIS_Part1_SponsorDetails'(
'ctrisId': 1473,
'sponsorName': "GSK R&D Ltd",
'organizationType': "Commercial",
'thirdPartyOrgDetails': {
'type!{urn:com:appian:types:CTRIS}CTRIS_Part1_Sponsor_ThirdPartyOrg'(
'ctrisId': 1473,
'orgId': "Test Organisation ID",
'orgName': "Test Name of organisation",
'duties': "Statistical Analysis,Q/A auditing",
'tpAddress': 'type!{urn:com:appian:types:CTRIS}CTRIS_AddressDetails'(
'ctrisId': 1473,
'context': "Third Party Organisations associated with the trial",
'addressLine1': "Address: Street name",
'country': "USA",
'phone': "1234567",
'email': "test@gsk.com"
),
),
'type!{urn:com:appian:types:CTRIS}CTRIS_Part1_Sponsor_ThirdPartyOrg'(
'ctrisId': 1473,
'orgId': "Test Organisation ID 2",
'orgName': "Test Name of organisation 2",
'duties': "Safety reporting,E-Data capture",
'tpAddress': 'type!{urn:com:appian:types:CTRIS}CTRIS_AddressDetails'(
'ctrisId': 1473,
'context': "Third Party Organisations associated with the trial",
'addressLine1': "Address: Street name 2",
'city': "Town/City 2",
'postalCode': "12345",
'country': "India",
'phone': "12345"
)
)
},
'orgSPORId': "ORG-100005535"
)
}

Based on the above code snippet, I need to delete the above highlighted rows.

currently I'm using the below code to delete which is erroring out. Could you please provide me the proper code to achieve this requirement.