Set "editor.contentFilter.allowIFrame" value false, restrict insertion <iframe> tag by User and remove <iframe> tag automatically.
synapeditor.config.js
{
'editor.contentFilter.allowIFrame': false
}
Set "editor.contentFilter.allowIScript" value false, restrict insertion <script> tag by Use rand remove <script> tag automatically.
synapeditor.config.js
{
'editor.contentFilter.allowScript': false
}