Open up your editing window by adding a project log or instructions etc.

Write your post, either until you get to the point you want to add strikethrough text or the whole thing.

We can do all the strikethrough at the end.

Now click the <> button at the top of your editing box. If your draft post disappears, don't worry (yet) - scroll up to see if it has been turned into plain text at the top.

Disclaimer - I use imgur to link my images in, so I don't know what effect this has on other methods of inserting images

find the text you want to strikethrough and before it type:

<del>

and after it type

</del>

Then repeat for any other sections you may want in strikethrough. When you have finished, press the <> button again and your nicely formatted post should reappear.

Good luck.