One of the best things about using blogs as writing spaces is that you can encourage a process of continual revision. Editing existing blog posts is easy on any platform; below are some tips about editing existing posts at Blogger.
Open a post for editing. To open any post for editing, just click on it in the Posts view of the dashboard. It's that simple!
In the old dashboard, there is an actual edit link if you hover over the post, but you don't have to use that link; just click on the post title and it opens that post for editing:
There are no longer edit/delete/view hover links; instead, you just click on the item to open it for editing.
In the old editor, the Tx button is at the far right of the editing menu:
Just highlight the whole post, then hit the Tx button, and that will strip away the formatting. You might need to go in and remove extra line breaks that get added, along with any bold, italics, etc. that you wanted.
The "pencil icon. One of the reasons I continue to use an "old" Blogger template (one that predates the latest templates which use mobile-first design principles) is that those templates feature a pencil icon in each blog post (visible only to the blog author) which allows you to instantly open the post for editing.
Spellcheck. Finally, this is not exactly related to editing an existing post, but you might be wondering about a spellcheck in Blogger. There is not a spellcheck feature; instead, you need to turn on the spellcheck feature in your browser, which will then provide the red squiggle for typos when you edit in Blogger. So if I type spellcheckk here in Chrome, I get the red squiggle, and if I then right-mouse click on that word, I get the following menu options:
Next up: editing post dates and labels for navigation purposes!