Annotation delete all after flatten

I am using the following below standard code with a documentloaded listener, and this is prior to loading new annoations from my database. This is because i want to strip user annotations (and comments) that a user may have imported themselves from extrenal party software. The flattening of annotations is working but the but not the following -“annotationManager.deleteAnnotations(annotationManager.getAnnotationsList());” as i can see both flattened and annotations overlapped on the pdf in webviewer. Do you know what i could be doing wrong?

WebViewer({
fullAPI: true,
// other constructor options
}, viewerElement).then(instance => {
const { documentViewer, PDFNet, annotationManager } = instance.Core;

document.getElementById(‘myBtn’).addEventListener(‘click’, async () => {
await PDFNet.initialize();
const doc = await documentViewer.getDocument().getPDFDoc();

// export annotations from the document
const annots = await annotationManager.exportAnnotations();

// Run PDFNet methods with memory management
await PDFNet.runWithCleanup(async () => {

  // lock the document before a write operation
  // runWithCleanup will auto unlock when complete
  doc.lock(); 

  // import annotations to PDFNet
  const fdf_doc = await PDFNet.FDFDoc.createFromXFDF(annots);
  await doc.fdfUpdate(fdf_doc);

  // flatten all annotations in the document
  await doc.flattenAnnotations();

  // or optionally only flatten forms
  // await doc.flattenAnnotations(true);

  // clear the original annotations
  annotationManager.deleteAnnotations(annotationManager.getAnnotationsList());

  // optionally only clear widget annotations if forms were only flattened
  // const widgetAnnots = annots.filter(a => a instanceof Annotations.WidgetAnnotation);
  // annotationManager.deleteAnnotations(widgetAnnots);
});

// clear the cache (rendered) data with the newly updated document
documentViewer.refreshAll();

// Update viewer to render with the new document
documentViewer.updateView();

// Refresh searchable and selectable text data with the new document
documentViewer.getDocument().refreshTextData();

});
});