In some documents (I'm working with ) there is a ProtectForm attribute set, which persists after saving .doc to .odt, which disables editing of any content outside of some kind of form "fields". "Design mode" doesn't work, and "Format > Sections" menu item is greyed out. Nothing else worked, and I've found a mention of this (,) and a fix in  which works. This implies that there is no method (or no easily visible one) to change that flag inside of Writer.
Steps to reproduce:
1. Open a document
2. Try to edit something outside of fields
3. Try to disable this protection
Editing is prohibited, and there is no visible way to disable protection without manual editing of .odt.
There is a way to do this.
Operating System: Linux (Other)
Version: 126.96.36.199 release
Even if I manage to change this flag with editing of settings.xml, there is an invisible symbols at start and end of these "fields" which cannot be removed.
Confirmed as an enhancement.
Win 7 64-bit Version: 188.8.131.52.alpha1+
Build ID: b7d8a58ff2698ffc6e22943f64aa97c5ea253bd9
TinderBox: Win-x86@42, Branch:master, Time: 2014-11-05_00:40:38
(In reply to Nikolay Amiantov from comment #0)
> Current behavior:
> Editing is prohibited, and there is no visible way to disable protection
> without manual editing of .odt.
Since LibreOffice version ??(4.4?) there is Tools > Options > Writer > Formatting Aids .. Protected Areas.
Would that fit your needs, and can we set to Resolved?
Oliver Specht committed a patch related to this issue.
It has been pushed to "master":
tdf#81833: form protection can be modified as compatibility option
It will be available in 5.2.0.
The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.
Backport to libreoffice-5-1: https://cgit.freedesktop.org/libreoffice/core/commit/?h=libreoffice-5-1&id=c0ffa8c3a10294b64b6e1a66f8d3c18098974cd6