Deleting everyhting and emptying inbox in Proton Email is a hassle. This moves everything to Trash. Use only if you understand the consequences

delete.js

  async function deleteAllEmails() {
    while (true) {
      // Click the label wrapping the select-all checkbox
      const label = document.querySelector('label[for="idSelectAll"]');
      if (!label) { console.log('No select-all found. Done.'); break; }
      label.click();

      await new Promise(r => setTimeout(r, 1000));

      // Look for trash button
      let trashBtn = document.querySelector('[data-testid="toolbar:movetotrash"]');

      // If no trash button, try clicking first individual checkbox instead
      if (!trashBtn) {
        console.log('Label click failed, trying individual checkboxes...');
        const checkboxes = document.querySelectorAll('input[type="checkbox"]:not(#idSelectAll)');
        checkboxes.forEach(cb => cb.click());
        await new Promise(r => setTimeout(r, 1000));
        trashBtn = document.querySelector('[data-testid="toolbar:movetotrash"]');
      }

      if (!trashBtn) { console.log('No trash button. Inbox may be empty.'); break; }

      trashBtn.click();

      // Handle confirmation dialog if any
      await new Promise(r => setTimeout(r, 1000));
      const confirmBtn = document.querySelector('.modal-two-dialog button.button-solid-norm, [data-testid*="delete"] button');
      if (confirmBtn) confirmBtn.click();

      // Wait for deletion to process
      console.log('Deleting batch... waiting...');
      await new Promise(r => setTimeout(r, 3000));

      // Check if empty
      const remaining = document.querySelectorAll('input[type="checkbox"]:not(#idSelectAll)');
      if (remaining.length === 0) { console.log('Inbox is empty!'); break; }

      console.log(`${remaining.length} emails remaining, continuing...`);
    }
  }

  deleteAllEmails();