The subscription can be suspended for a while. After this it can be reactivated or cancelled. There is another endpoint to cancel a subscription permanently.

In order to suspend the subscription you must call the endpoint POST /api/v2/Payment/Subscriptions/{id}/suspend:

Request
POST /api/v2/Payment/Subscriptions/SUB_WNFRN9X2ZV8W3411BVM4D8UO6WJUOP/suspend HTTP/1.1
Host: connect-testing.secuconnect.com
Authorization: Bearer qb56tjj1bcvo9n2nj4u38k84lo
Content-Type: application/json
Accept: application/json
 
{
"reason": "Item out of stock"
}

The field reason is optional.

If everthing is fine, the API responds with 200 OK, and the representation of the Subcription object:

Request
HTTP/1.1 200 OK
Content-Type: application/json
...
 
{
"object": "payment.subscriptions",
"id": "SUB_WNFRN9X2ZV8W3411BVM4D8UO6WJUOP",
"status": "suspended",
"reason": "Item out of stock"
}

The status suspended tells about the temporary deactivation.