This assumes you have used the REST API to obtain an OAuth bearer token. Let's say the bearer token is sha256~0Rs__hPuXmBD3TJTXNDisC7wRBN-nrFnYTxgdBrFT-U.

Before deleting a secret, you will probably want to list the secrets in a namespace to ensure the secret you want to delete exists. Here is how you would list the secrets in the "default" namespace using the curl REST API.

curl
--insecure
--request GET
--header "Accept: application/json"
--header "Authorization: Bearer sha256~0Rs__hPuXmBD3TJTXNDisC7wRBN-nrFnYTxgdBrFT-U"
--url "https://api.lab001.op.example.com:6443/api/v1/namespaces/default/secrets"

If the items array contains key value pairs, this means the namespace contains one or more secrets.

{
  "kind": "Secret",
  "apiVersion": "v1",
  "metadata": {
    "name": "mysecret",
    "namespace": "default",
    "selfLink": "/api/v1/namespaces/default/secrets/mysecret",
    "uid": "cf858bde-be0f-40ae-a882-2daa815335a4",
    "resourceVersion": "136899647",
    "creationTimestamp": "2021-11-18T11:51:46Z",
    "managedFields": [
      {
        "manager": "kubectl-create",
        "operation": "Update",
        "apiVersion": "v1",
        "time": "2021-11-18T11:51:46Z",
        "fieldsType": "FieldsV1",
        "fieldsV1": {"f:data":{".":{},"f:foo":{}},"f:type":{}}
      }
    ]
  },
  "data": {
    "foo": "YmFy"
  },
  "type": "Opaque"
}

Or to return a specific secret, such as "mysecret".

curl
--insecure
--request GET
--header "Accept: application/json"
--header "Authorization: Bearer sha256~0Rs__hPuXmBD3TJTXNDisC7wRBN-nrFnYTxgdBrFT-U"
--url "https://api.lab001.op.example.com:6443/api/v1/namespaces/default/secrets/mysecret"

Here is how you would delete "mysecret".

curl
--insecure
--request DELETE
--header "Accept: application/json"
--header "Authorization: Bearer sha256~0Rs__hPuXmBD3TJTXNDisC7wRBN-nrFnYTxgdBrFT-U"
--url "https://api.lab001.op.example.com:6443/api/v1/namespaces/default/secrets/mysecret"

If the delete is successful, something like this should be returned.

{
  "kind": "Status",
  "apiVersion": "v1",
  "metadata": {
    
  },
  "status": "Success",
  "details": {
    "name": "mysecret",
    "kind": "secrets",
    "uid": "49fadd8b-bc73-4880-ae83-e4c8fed726b9"
  }
}

If the delete fails, such as when the secret does not exist, something like this should be returned.

{
  "kind": "Status",
  "apiVersion": "v1",
  "metadata": {
    
  },
  "status": "Failure",
  "message": "secrets \"bogus\" not found",
  "reason": "NotFound",
  "details": {
    "name": "bogus",
    "kind": "secrets"
  },
  "code": 404
}