delete (name, isLowerCase) {
    this.sortedMap = null
    if (!isLowerCase) name = name.toLowerCase()

    if (name === 'set-cookie') {
      this.cookies = null
    }

    this.headersMap.delete(name)
  }
@see https://fetch.spec.whatwg.org/#concept-header-list-delete
@param {string} name
@param {boolean} isLowerCase