curl -X DELETE \
  "https://console.trychert.com/api/v1/chats/ch_01H.../participants/%2B14155551234" \
  -H "x-chert-tenant: $TENANT" \
  -H "x-chert-signature: v1,$TS,$SIG"

const ts = Math.floor(Date.now() / 1000)
const body = ""
const sig = crypto.createHmac("sha256", SIGNING_SECRET).update(`${ts}.${body}`).digest("hex")
const address = encodeURIComponent("+14155551234")
const res = await fetch(
  `https://console.trychert.com/api/v1/chats/${chatId}/participants/${address}`,
  {
    method: "DELETE",
    headers: {
      "x-chert-tenant": TENANT_SLUG,
      "x-chert-signature": `v1,${ts},${sig}`,
    },
  },
)

import hmac, hashlib, time, urllib.parse, requests
ts = int(time.time())
body = ""
sig = hmac.new(SIGNING_SECRET.encode(), f"{ts}.{body}".encode(), hashlib.sha256).hexdigest()
addr = urllib.parse.quote("+14155551234", safe="")
r = requests.delete(
    f"https://console.trychert.com/api/v1/chats/{chat_id}/participants/{addr}",
    headers={
        "x-chert-tenant": TENANT_SLUG,
        "x-chert-signature": f"v1,{ts},{sig}",
    },
)

{
  "chat_id": "ch_01H...",
  "removed": "+14155551234",
  "participants": ["+14155550100", "+14155550200"]
}