Remove annotation from document on iOS

To remove an annotation from a document.

PTPDFDoc *doc = [[PTPDFDoc alloc] initWithFilepath: filename];
PTPage *page = [doc GetPage:1];

// remove by index
[page AnnotRemoveWithIndex:0];

// remove by annotation
PTAnnot *annotation = [page GetAnnot:0];
[page AnnotRemoveWithAnnot:annotation];