Disable learning mode from REST API

This can be accomplished via the following steps:

Get the policy id for the policy or policies:

All policies:

https://{{bigip_mgmt}}/mgmt/tm/asm/policies?$select=name,id

Filter for single policy by name:

https://{{bigip_mgmt}}/mgmt/tm/asm/policies?$filter=name eq 'Child_1'&$select=name,id

{
    "kind": "tm:asm:policies:policycollectionstate",
    "selfLink": "https://localhost/mgmt/tm/asm/policies?$select=name%2Cid&ver=13.1.1&$filter=name%20eq%20'Child_1'",
    "totalItems": 1,
    "items": [
        {
            "kind": "tm:asm:policies:policystate",
            "selfLink": "https://localhost/mgmt/tm/asm/policies/N92Kq8isMxe18Nzg3GzqTg?ver=13.1.1",
            "name": "Child_1",
            "id": "N92Kq8isMxe18Nzg3GzqTg"
        }
    ]
}

Then access the learning mode:

https://{{bigip_mgmt}}/mgmt/tm/asm/policies/N92Kq8isMxe18Nzg3GzqTg/policy-builder?$select=learningMode

{
    "kind": "tm:asm:policies:policy-builder:policy-builderstate",
    "selfLink": "https://localhost/mgmt/tm/asm/policies/N92Kq8isMxe18Nzg3GzqTg/policy-builder?$select=learningMode&ver=13.1.1",
    "learningMode": "manual"
}

Now change via Patch:

https://{{bigip_mgmt}}/mgmt/tm/asm/policies/N92Kq8isMxe18Nzg3GzqTg/policy-builder

Body:

{
  "learningMode": "disabled"
 }

Check the change has taken place:

https://{{bigip_mgmt}}/mgmt/tm/asm/policies/N92Kq8isMxe18Nzg3GzqTg/policy-builder?$select=learningMode

{
    "kind": "tm:asm:policies:policy-builder:policy-builderstate",
    "selfLink": "https://localhost/mgmt/tm/asm/policies/N92Kq8isMxe18Nzg3GzqTg/policy-builder?$select=learningMode&ver=13.1.1",
    "learningMode": "disabled"
}

Ensure you apply the policy to enforce the change.