Can an EU member officially give up pursuing Euro/Eurozone?
No (...ish). The current stance of the EU Commission is:
All EU Member States, except Denmark and the United Kingdom, are
required to adopt the euro and join the euro area. To do this they
must meet certain conditions known as 'convergence criteria'.
The exceptions for the UK and Denmark are due to negotiated opt-outs:
All member states, other than Denmark and the United Kingdom, have
either adopted the euro or are legally bound to do so. During the
negotiations of the Maastricht Treaty of 1992 the UK secured an
opt-out, while a protocol gave Denmark the right to decide if and
when they would join the euro. Denmark subsequently notified the
Council of the European Communities of their decision to opt out of
the euro, and this was included as part of the 1992 Edinburgh
Agreement, a Decision of Council, reached following the Maastricht
Treaty's initial rejection in a 1992 Danish referendum. The purpose of
the agreement was to assist in its approval in a second referendum,
which it did.
However this does not imply the existence of a mechanism to enforce the enlargement. The euro zone is still very much a strongly political notion whose adoption is largely a diplomatic issue. Nevertheless there is some pressure to make members join the euro zone. Just check Jean-Claude Juncker's State of the Union speech last year (2017).
If we want the euro to unite rather than divide our continent, then it
should be more than the currency of a select group of countries. The
euro is meant to be the single currency of the European Union as a
whole. All but two of our Member States are required and entitled to
join the euro once they fulfill the conditions.
The reason he said so is because some countries do not want to lose monetary sovereignty. But understand that his policy is not a consensus in the European Union. The large majority argues for more integration, but some want it faster and others want it slower.
EDIT: yesterday, and just a few days after this answer was written, the European Commission released a new fact sheet named The 2018 Convergence Report: Review of Member States' progress towards euro adoption where a question very similar to yours was answered. Here goes the quote:
Are Member States obliged to join the euro?
In principle, all Member States that do not have an opt-out clause
(i.e. United Kingdom and Denmark) have committed to adopt the euro
once they fulfill the necessary conditions. However, it is up to
individual countries to calibrate their path towards the euro and no
timetable is prescribed.
The Member States that joined the EU in 2004, 2007 and 2013, after the
euro was launched, did not meet the conditions for entry to the euro
area at the time of their accession. Therefore, their Treaties of
Accession allow them time to make the necessary adjustments.