Уведомление о расторжении нужно; договор хранения расторгнут завтра.

Расторжении is in the prepositional case because it follows о.

With nouns like уведомление, сообщение, информация, Russian often uses о + prepositional to mean about / regarding the topic:

• уведомление о расторжении = notice of termination
• сообщение об изменениях = message about changes
• информация о договоре = information about the contract

So literally, уведомление о расторжении is something like notice regarding termination.

In Russian, the verb to be is normally omitted in the present tense.

So:

• Договор готов. = The contract is ready.
• Уведомление нужно. = The notice is needed.

Russian does not usually say a present-tense equivalent of is here. English needs it; Russian usually does not.

Because уведомление is neuter singular, and нужно agrees with it.

Compare:

• паспорт нужен = the passport is needed
• справка нужна = the certificate is needed
• уведомление нужно = the notice is needed
• документы нужны = the documents are needed

So нужно matches the gender and number of уведомление.

Договор хранения is a fixed legal-style expression meaning storage contract or contract of storage.

Here:

• договор = contract, agreement
• хранения = genitive singular of хранение = storage, keeping

Russian very often names types of contracts with this pattern:

• договор аренды = lease agreement
• договор страхования = insurance contract
• договор купли-продажи = purchase and sale agreement

So хранения is in the genitive because it specifies what kind of contract it is.

Yes. Расторгнуть is a formal/legal verb meaning to terminate, to rescind, or to cancel a contract or legal relationship.

Typical examples:

• расторгнуть договор = terminate a contract
• расторгнуть соглашение = terminate an agreement
• расторгнуть брак = dissolve a marriage

The noun расторжение means termination / rescission.

This is not the most casual everyday verb; it sounds administrative, legal, or official.

Расторгнут is a short passive participle from расторгнуть.

It means something like:

• has been terminated
• is terminated
• in some contexts, will be terminated

Short passive participles are very common in formal Russian, especially in legal, business, and written styles.

Compare:

• Договор расторгнут. = The contract has been terminated.
• Сделка отменена. = The deal has been canceled.
• Документ подписан. = The document has been signed.

Because расторгнут is the short form, used as the predicate of the sentence.

• договор расторгнут = the contract is terminated

But расторгнутый is the full form, used more like an adjective before a noun:

• расторгнутый договор = a terminated contract

So:

• Договор расторгнут. = correct predicate use
• Расторгнутый договор лежит на столе. = correct attributive use

This is probably the biggest thing an English speaker would notice.

In neutral standard Russian, with завтра, many speakers would more naturally say:

• Договор хранения будет расторгнут завтра.

That clearly means The storage contract will be terminated tomorrow.

The version without будет sounds compressed, official, headline-like, or elliptical. It is understandable, but it is less neutral and more stylistically marked.

So if you are learning everyday standard Russian, будет расторгнут завтра is the safer pattern.

Yes. Short passive participles agree in gender and number.

Here договор is masculine singular, so we get расторгнут.

Compare:

• договор расторгнут = masculine singular
• сделка расторгнута = feminine singular
• соглашение расторгнуто = neuter singular
• договоры расторгнуты = plural

So the ending tells you what noun it matches.

Yes. Russian word order is flexible, and changing it usually changes emphasis, not the basic meaning.

For example:

• Договор хранения будет расторгнут завтра. = neutral
• Завтра договор хранения будет расторгнут. = emphasizes tomorrow
• Уведомление о расторжении нужно. = neutral
• Нужно уведомление о расторжении. = emphasizes needed / required

That said, in legal or formal language, writers often prefer more fixed, tidy word order.

Russian has no articles.

So:

• уведомление can mean a notice or the notice
• договор хранения can mean a storage contract or the storage contract

The exact meaning depends on context.

That is why English translations have to choose between a and the, even though Russian does not mark that directly.